1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "chrome/browser/memory_details.h"
6
7#include "base/bind.h"
8#include "base/file_version_info.h"
9#include "base/metrics/histogram.h"
10#include "base/strings/string_util.h"
11#include "base/strings/stringprintf.h"
12#include "base/strings/utf_string_conversions.h"
13#include "chrome/browser/extensions/extension_service.h"
14#include "chrome/browser/profiles/profile.h"
15#include "chrome/common/url_constants.h"
16#include "components/nacl/common/nacl_process_type.h"
17#include "content/public/browser/browser_child_process_host_iterator.h"
18#include "content/public/browser/browser_thread.h"
19#include "content/public/browser/child_process_data.h"
20#include "content/public/browser/navigation_controller.h"
21#include "content/public/browser/navigation_entry.h"
22#include "content/public/browser/render_process_host.h"
23#include "content/public/browser/render_view_host.h"
24#include "content/public/browser/render_widget_host_iterator.h"
25#include "content/public/browser/web_contents.h"
26#include "content/public/common/bindings_policy.h"
27#include "extensions/browser/process_manager.h"
28#include "extensions/browser/process_map.h"
29#include "extensions/browser/view_type_utils.h"
30#include "extensions/common/extension.h"
31#include "grit/chromium_strings.h"
32#include "grit/generated_resources.h"
33#include "ui/base/l10n/l10n_util.h"
34
35#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
36#include "content/public/browser/zygote_host_linux.h"
37#endif
38
39using base::StringPrintf;
40using content::BrowserChildProcessHostIterator;
41using content::BrowserThread;
42using content::NavigationEntry;
43using content::RenderViewHost;
44using content::RenderWidgetHost;
45using content::WebContents;
46using extensions::Extension;
47
48// static
49std::string ProcessMemoryInformation::GetRendererTypeNameInEnglish(
50    RendererProcessType type) {
51  switch (type) {
52    case RENDERER_NORMAL:
53      return "Tab";
54    case RENDERER_CHROME:
55      return "Tab (Chrome)";
56    case RENDERER_EXTENSION:
57      return "Extension";
58    case RENDERER_DEVTOOLS:
59      return "Devtools";
60    case RENDERER_INTERSTITIAL:
61      return "Interstitial";
62    case RENDERER_BACKGROUND_APP:
63      return "Background App";
64    case RENDERER_UNKNOWN:
65    default:
66      NOTREACHED() << "Unknown renderer process type!";
67      return "Unknown";
68  }
69}
70
71// static
72std::string ProcessMemoryInformation::GetFullTypeNameInEnglish(
73    int process_type,
74    RendererProcessType rtype) {
75  if (process_type == content::PROCESS_TYPE_RENDERER)
76    return GetRendererTypeNameInEnglish(rtype);
77  return content::GetProcessTypeNameInEnglish(process_type);
78}
79
80ProcessMemoryInformation::ProcessMemoryInformation()
81    : pid(0),
82      num_processes(0),
83      is_diagnostics(false),
84      process_type(content::PROCESS_TYPE_UNKNOWN),
85      renderer_type(RENDERER_UNKNOWN) {
86}
87
88ProcessMemoryInformation::~ProcessMemoryInformation() {}
89
90bool ProcessMemoryInformation::operator<(
91    const ProcessMemoryInformation& rhs) const {
92  return working_set.priv < rhs.working_set.priv;
93}
94
95ProcessData::ProcessData() {}
96
97ProcessData::ProcessData(const ProcessData& rhs)
98    : name(rhs.name),
99      process_name(rhs.process_name),
100      processes(rhs.processes) {
101}
102
103ProcessData::~ProcessData() {}
104
105ProcessData& ProcessData::operator=(const ProcessData& rhs) {
106  name = rhs.name;
107  process_name = rhs.process_name;
108  processes = rhs.processes;
109  return *this;
110}
111
112// About threading:
113//
114// This operation will hit no fewer than 3 threads.
115//
116// The BrowserChildProcessHostIterator can only be accessed from the IO thread.
117//
118// The RenderProcessHostIterator can only be accessed from the UI thread.
119//
120// This operation can take 30-100ms to complete.  We never want to have
121// one task run for that long on the UI or IO threads.  So, we run the
122// expensive parts of this operation over on the file thread.
123//
124void MemoryDetails::StartFetch(UserMetricsMode user_metrics_mode) {
125  // This might get called from the UI or FILE threads, but should not be
126  // getting called from the IO thread.
127  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::IO));
128  user_metrics_mode_ = user_metrics_mode;
129
130  // In order to process this request, we need to use the plugin information.
131  // However, plugin process information is only available from the IO thread.
132  BrowserThread::PostTask(
133      BrowserThread::IO, FROM_HERE,
134      base::Bind(&MemoryDetails::CollectChildInfoOnIOThread, this));
135}
136
137MemoryDetails::~MemoryDetails() {}
138
139std::string MemoryDetails::ToLogString() {
140  std::string log;
141  log.reserve(4096);
142  ProcessMemoryInformationList processes = ChromeBrowser()->processes;
143  // Sort by memory consumption, low to high.
144  std::sort(processes.begin(), processes.end());
145  // Print from high to low.
146  for (ProcessMemoryInformationList::reverse_iterator iter1 =
147          processes.rbegin();
148       iter1 != processes.rend();
149       ++iter1) {
150    log += ProcessMemoryInformation::GetFullTypeNameInEnglish(
151            iter1->process_type, iter1->renderer_type);
152    if (!iter1->titles.empty()) {
153      log += " [";
154      for (std::vector<base::string16>::const_iterator iter2 =
155               iter1->titles.begin();
156           iter2 != iter1->titles.end(); ++iter2) {
157        if (iter2 != iter1->titles.begin())
158          log += "|";
159        log += base::UTF16ToUTF8(*iter2);
160      }
161      log += "]";
162    }
163    log += StringPrintf(" %d MB private, %d MB shared",
164                        static_cast<int>(iter1->working_set.priv) / 1024,
165                        static_cast<int>(iter1->working_set.shared) / 1024);
166#if defined(OS_CHROMEOS)
167    log += StringPrintf(", %d MB swapped",
168                        static_cast<int>(iter1->working_set.swapped) / 1024);
169#endif
170    log += "\n";
171  }
172  return log;
173}
174
175void MemoryDetails::CollectChildInfoOnIOThread() {
176  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
177
178  std::vector<ProcessMemoryInformation> child_info;
179
180  // Collect the list of child processes. A 0 |handle| means that
181  // the process is being launched, so we skip it.
182  for (BrowserChildProcessHostIterator iter; !iter.Done(); ++iter) {
183    ProcessMemoryInformation info;
184    if (!iter.GetData().handle)
185      continue;
186    info.pid = base::GetProcId(iter.GetData().handle);
187    if (!info.pid)
188      continue;
189
190    info.process_type = iter.GetData().process_type;
191    info.renderer_type = ProcessMemoryInformation::RENDERER_UNKNOWN;
192    info.titles.push_back(iter.GetData().name);
193    child_info.push_back(info);
194  }
195
196  // Now go do expensive memory lookups from the file thread.
197  BrowserThread::PostTask(
198      BrowserThread::FILE, FROM_HERE,
199      base::Bind(&MemoryDetails::CollectProcessData, this, child_info));
200}
201
202void MemoryDetails::CollectChildInfoOnUIThread() {
203  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
204
205#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
206  const pid_t zygote_pid = content::ZygoteHost::GetInstance()->GetPid();
207#endif
208
209  ProcessData* const chrome_browser = ChromeBrowser();
210  // Get more information about the process.
211  for (size_t index = 0; index < chrome_browser->processes.size();
212      index++) {
213    // Check if it's a renderer, if so get the list of page titles in it and
214    // check if it's a diagnostics-related process.  We skip about:memory pages.
215    // Iterate the RenderProcessHosts to find the tab contents.
216    ProcessMemoryInformation& process =
217        chrome_browser->processes[index];
218
219    scoped_ptr<content::RenderWidgetHostIterator> widgets(
220        RenderWidgetHost::GetRenderWidgetHosts());
221    while (content::RenderWidgetHost* widget = widgets->GetNextHost()) {
222      content::RenderProcessHost* render_process_host =
223          widget->GetProcess();
224      DCHECK(render_process_host);
225      // Ignore processes that don't have a connection, such as crashed tabs.
226      if (!render_process_host->HasConnection() ||
227          process.pid != base::GetProcId(render_process_host->GetHandle())) {
228        continue;
229      }
230      process.process_type = content::PROCESS_TYPE_RENDERER;
231      Profile* profile =
232          Profile::FromBrowserContext(
233              render_process_host->GetBrowserContext());
234      ExtensionService* extension_service = profile->GetExtensionService();
235      extensions::ProcessMap* extension_process_map = NULL;
236      // No extensions on Android. So extension_service can be NULL.
237      if (extension_service)
238          extension_process_map = extensions::ProcessMap::Get(profile);
239
240      // The RenderProcessHost may host multiple WebContentses.  Any
241      // of them which contain diagnostics information make the whole
242      // process be considered a diagnostics process.
243      if (!widget->IsRenderView())
244        continue;
245
246      RenderViewHost* host = RenderViewHost::From(widget);
247      WebContents* contents = WebContents::FromRenderViewHost(host);
248      GURL url;
249      if (contents) {
250        url = contents->GetURL();
251        SiteData* site_data =
252            &chrome_browser->site_data[contents->GetBrowserContext()];
253        SiteDetails::CollectSiteInfo(contents, site_data);
254      }
255      extensions::ViewType type = extensions::GetViewType(contents);
256      if (host->GetEnabledBindings() & content::BINDINGS_POLICY_WEB_UI) {
257        process.renderer_type = ProcessMemoryInformation::RENDERER_CHROME;
258      } else if (extension_process_map &&
259                 extension_process_map->Contains(host->GetProcess()->GetID())) {
260        // For our purposes, don't count processes containing only hosted apps
261        // as extension processes. See also: crbug.com/102533.
262        std::set<std::string> extension_ids =
263            extension_process_map->GetExtensionsInProcess(
264            host->GetProcess()->GetID());
265        for (std::set<std::string>::iterator iter = extension_ids.begin();
266             iter != extension_ids.end(); ++iter) {
267          const Extension* extension =
268              extension_service->GetExtensionById(*iter, false);
269          if (extension && !extension->is_hosted_app()) {
270            process.renderer_type =
271                ProcessMemoryInformation::RENDERER_EXTENSION;
272            break;
273          }
274        }
275      }
276      if (extension_process_map &&
277          extension_process_map->Contains(host->GetProcess()->GetID())) {
278        const Extension* extension =
279            extension_service->extensions()->GetByID(url.host());
280        if (extension) {
281          base::string16 title = base::UTF8ToUTF16(extension->name());
282          process.titles.push_back(title);
283          process.renderer_type =
284              ProcessMemoryInformation::RENDERER_EXTENSION;
285          continue;
286        }
287      }
288
289      if (!contents) {
290        process.renderer_type =
291            ProcessMemoryInformation::RENDERER_INTERSTITIAL;
292        continue;
293      }
294
295      if (type == extensions::VIEW_TYPE_BACKGROUND_CONTENTS) {
296        process.titles.push_back(base::UTF8ToUTF16(url.spec()));
297        process.renderer_type =
298            ProcessMemoryInformation::RENDERER_BACKGROUND_APP;
299        continue;
300      }
301
302      // Since we have a WebContents and and the renderer type hasn't been
303      // set yet, it must be a normal tabbed renderer.
304      if (process.renderer_type == ProcessMemoryInformation::RENDERER_UNKNOWN)
305        process.renderer_type = ProcessMemoryInformation::RENDERER_NORMAL;
306
307      base::string16 title = contents->GetTitle();
308      if (!title.length())
309        title = l10n_util::GetStringUTF16(IDS_DEFAULT_TAB_TITLE);
310      process.titles.push_back(title);
311
312      // We need to check the pending entry as well as the virtual_url to
313      // see if it's a chrome://memory URL (we don't want to count these in
314      // the total memory usage of the browser).
315      //
316      // When we reach here, chrome://memory will be the pending entry since
317      // we haven't responded with any data such that it would be committed.
318      // If you have another chrome://memory tab open (which would be
319      // committed), we don't want to count it either, so we also check the
320      // last committed entry.
321      //
322      // Either the pending or last committed entries can be NULL.
323      const NavigationEntry* pending_entry =
324          contents->GetController().GetPendingEntry();
325      const NavigationEntry* last_committed_entry =
326          contents->GetController().GetLastCommittedEntry();
327      if ((last_committed_entry &&
328           LowerCaseEqualsASCII(last_committed_entry->GetVirtualURL().spec(),
329                                chrome::kChromeUIMemoryURL)) ||
330          (pending_entry &&
331           LowerCaseEqualsASCII(pending_entry->GetVirtualURL().spec(),
332                                chrome::kChromeUIMemoryURL))) {
333        process.is_diagnostics = true;
334      }
335    }
336
337#if defined(OS_POSIX) && !defined(OS_MACOSX) && !defined(OS_ANDROID)
338    if (process.pid == zygote_pid) {
339      process.process_type = content::PROCESS_TYPE_ZYGOTE;
340    }
341#endif
342  }
343
344  // Get rid of other Chrome processes that are from a different profile.
345  for (size_t index = 0; index < chrome_browser->processes.size();
346      index++) {
347    if (chrome_browser->processes[index].process_type ==
348        content::PROCESS_TYPE_UNKNOWN) {
349      chrome_browser->processes.erase(
350          chrome_browser->processes.begin() + index);
351      index--;
352    }
353  }
354
355  if (user_metrics_mode_ == UPDATE_USER_METRICS)
356    UpdateHistograms();
357
358  OnDetailsAvailable();
359}
360
361void MemoryDetails::UpdateHistograms() {
362  // Reports a set of memory metrics to UMA.
363  // Memory is measured in KB.
364
365  const ProcessData& browser = *ChromeBrowser();
366  size_t aggregate_memory = 0;
367  int chrome_count = 0;
368  int extension_count = 0;
369  int plugin_count = 0;
370  int pepper_plugin_count = 0;
371  int pepper_plugin_broker_count = 0;
372  int renderer_count = 0;
373  int other_count = 0;
374  int worker_count = 0;
375  int process_limit = content::RenderProcessHost::GetMaxRendererProcessCount();
376  for (size_t index = 0; index < browser.processes.size(); index++) {
377    int sample = static_cast<int>(browser.processes[index].working_set.priv);
378    aggregate_memory += sample;
379    switch (browser.processes[index].process_type) {
380      case content::PROCESS_TYPE_BROWSER:
381        UMA_HISTOGRAM_MEMORY_KB("Memory.Browser", sample);
382        continue;
383      case content::PROCESS_TYPE_RENDERER: {
384        ProcessMemoryInformation::RendererProcessType renderer_type =
385            browser.processes[index].renderer_type;
386        switch (renderer_type) {
387          case ProcessMemoryInformation::RENDERER_EXTENSION:
388            UMA_HISTOGRAM_MEMORY_KB("Memory.Extension", sample);
389            extension_count++;
390            continue;
391          case ProcessMemoryInformation::RENDERER_CHROME:
392            UMA_HISTOGRAM_MEMORY_KB("Memory.Chrome", sample);
393            chrome_count++;
394            continue;
395          case ProcessMemoryInformation::RENDERER_UNKNOWN:
396            NOTREACHED() << "Unknown renderer process type.";
397            continue;
398          case ProcessMemoryInformation::RENDERER_NORMAL:
399          default:
400            // TODO(erikkay): Should we bother splitting out the other subtypes?
401            UMA_HISTOGRAM_MEMORY_KB("Memory.Renderer", sample);
402            renderer_count++;
403            continue;
404        }
405      }
406      case content::PROCESS_TYPE_PLUGIN:
407        UMA_HISTOGRAM_MEMORY_KB("Memory.Plugin", sample);
408        plugin_count++;
409        continue;
410      case content::PROCESS_TYPE_WORKER:
411        UMA_HISTOGRAM_MEMORY_KB("Memory.Worker", sample);
412        worker_count++;
413        continue;
414      case content::PROCESS_TYPE_UTILITY:
415        UMA_HISTOGRAM_MEMORY_KB("Memory.Utility", sample);
416        other_count++;
417        continue;
418      case content::PROCESS_TYPE_ZYGOTE:
419        UMA_HISTOGRAM_MEMORY_KB("Memory.Zygote", sample);
420        other_count++;
421        continue;
422      case content::PROCESS_TYPE_SANDBOX_HELPER:
423        UMA_HISTOGRAM_MEMORY_KB("Memory.SandboxHelper", sample);
424        other_count++;
425        continue;
426      case content::PROCESS_TYPE_GPU:
427        UMA_HISTOGRAM_MEMORY_KB("Memory.Gpu", sample);
428        other_count++;
429        continue;
430      case content::PROCESS_TYPE_PPAPI_PLUGIN:
431        UMA_HISTOGRAM_MEMORY_KB("Memory.PepperPlugin", sample);
432        pepper_plugin_count++;
433        continue;
434      case content::PROCESS_TYPE_PPAPI_BROKER:
435        UMA_HISTOGRAM_MEMORY_KB("Memory.PepperPluginBroker", sample);
436        pepper_plugin_broker_count++;
437        continue;
438      case PROCESS_TYPE_NACL_LOADER:
439        UMA_HISTOGRAM_MEMORY_KB("Memory.NativeClient", sample);
440        other_count++;
441        continue;
442      case PROCESS_TYPE_NACL_BROKER:
443        UMA_HISTOGRAM_MEMORY_KB("Memory.NativeClientBroker", sample);
444        other_count++;
445        continue;
446      default:
447        NOTREACHED();
448        continue;
449    }
450  }
451#if defined(OS_CHROMEOS)
452  // Chrome OS exposes system-wide graphics driver memory which has historically
453  // been a source of leak/bloat.
454  base::SystemMemoryInfoKB meminfo;
455  if (base::GetSystemMemoryInfo(&meminfo) && meminfo.gem_size != -1)
456    UMA_HISTOGRAM_MEMORY_MB("Memory.Graphics", meminfo.gem_size / 1024 / 1024);
457#endif
458
459  UMA_HISTOGRAM_COUNTS_100("Memory.ProcessLimit", process_limit);
460  UMA_HISTOGRAM_COUNTS_100("Memory.ProcessCount",
461      static_cast<int>(browser.processes.size()));
462  UMA_HISTOGRAM_COUNTS_100("Memory.ChromeProcessCount", chrome_count);
463  UMA_HISTOGRAM_COUNTS_100("Memory.ExtensionProcessCount", extension_count);
464  UMA_HISTOGRAM_COUNTS_100("Memory.OtherProcessCount", other_count);
465  UMA_HISTOGRAM_COUNTS_100("Memory.PluginProcessCount", plugin_count);
466  UMA_HISTOGRAM_COUNTS_100("Memory.PepperPluginProcessCount",
467      pepper_plugin_count);
468  UMA_HISTOGRAM_COUNTS_100("Memory.PepperPluginBrokerProcessCount",
469      pepper_plugin_broker_count);
470  UMA_HISTOGRAM_COUNTS_100("Memory.RendererProcessCount", renderer_count);
471  UMA_HISTOGRAM_COUNTS_100("Memory.WorkerProcessCount", worker_count);
472  // TODO(viettrungluu): Do we want separate counts for the other
473  // (platform-specific) process types?
474
475  int total_sample = static_cast<int>(aggregate_memory / 1000);
476  UMA_HISTOGRAM_MEMORY_MB("Memory.Total", total_sample);
477
478#if defined(OS_CHROMEOS)
479  UpdateSwapHistograms();
480#endif
481
482}
483
484#if defined(OS_CHROMEOS)
485void MemoryDetails::UpdateSwapHistograms() {
486  UMA_HISTOGRAM_BOOLEAN("Memory.Swap.HaveSwapped", swap_info_.num_writes > 0);
487  if (swap_info_.num_writes == 0)
488    return;
489
490  // Only record swap info when any swaps have happened, to give us more
491  // detail in the histograms.
492  const ProcessData& browser = *ChromeBrowser();
493  size_t aggregate_memory = 0;
494  for (size_t index = 0; index < browser.processes.size(); index++) {
495    int sample = static_cast<int>(browser.processes[index].working_set.swapped);
496    aggregate_memory += sample;
497    switch (browser.processes[index].process_type) {
498      case content::PROCESS_TYPE_BROWSER:
499        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Browser", sample);
500        continue;
501      case content::PROCESS_TYPE_RENDERER: {
502        ProcessMemoryInformation::RendererProcessType renderer_type =
503            browser.processes[index].renderer_type;
504        switch (renderer_type) {
505          case ProcessMemoryInformation::RENDERER_EXTENSION:
506            UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Extension", sample);
507            continue;
508          case ProcessMemoryInformation::RENDERER_CHROME:
509            UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Chrome", sample);
510            continue;
511          case ProcessMemoryInformation::RENDERER_UNKNOWN:
512            NOTREACHED() << "Unknown renderer process type.";
513            continue;
514          case ProcessMemoryInformation::RENDERER_NORMAL:
515          default:
516            UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Renderer", sample);
517            continue;
518        }
519      }
520      case content::PROCESS_TYPE_PLUGIN:
521        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Plugin", sample);
522        continue;
523      case content::PROCESS_TYPE_WORKER:
524        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Worker", sample);
525        continue;
526      case content::PROCESS_TYPE_UTILITY:
527        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Utility", sample);
528        continue;
529      case content::PROCESS_TYPE_ZYGOTE:
530        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Zygote", sample);
531        continue;
532      case content::PROCESS_TYPE_SANDBOX_HELPER:
533        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.SandboxHelper", sample);
534        continue;
535      case content::PROCESS_TYPE_GPU:
536        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.Gpu", sample);
537        continue;
538      case content::PROCESS_TYPE_PPAPI_PLUGIN:
539        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.PepperPlugin", sample);
540        continue;
541      case content::PROCESS_TYPE_PPAPI_BROKER:
542        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.PepperPluginBroker", sample);
543        continue;
544      case PROCESS_TYPE_NACL_LOADER:
545        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.NativeClient", sample);
546        continue;
547      case PROCESS_TYPE_NACL_BROKER:
548        UMA_HISTOGRAM_MEMORY_KB("Memory.Swap.NativeClientBroker", sample);
549        continue;
550      default:
551        NOTREACHED();
552        continue;
553    }
554  }
555
556  int total_sample = static_cast<int>(aggregate_memory / 1000);
557  UMA_HISTOGRAM_MEMORY_MB("Memory.Swap.Total", total_sample);
558
559  UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.Swap.CompressedDataSize",
560                              swap_info_.compr_data_size / (1024 * 1024),
561                              1, 4096, 50);
562  UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.Swap.OriginalDataSize",
563                              swap_info_.orig_data_size / (1024 * 1024),
564                              1, 4096, 50);
565  UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.Swap.MemUsedTotal",
566                              swap_info_.mem_used_total / (1024 * 1024),
567                              1, 4096, 50);
568  UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.Swap.NumReads",
569                              swap_info_.num_reads,
570                              1, 100000000, 100);
571  UMA_HISTOGRAM_CUSTOM_COUNTS("Memory.Swap.NumWrites",
572                              swap_info_.num_writes,
573                              1, 100000000, 100);
574
575  if (swap_info_.orig_data_size > 0 && swap_info_.compr_data_size > 0) {
576    UMA_HISTOGRAM_CUSTOM_COUNTS(
577        "Memory.Swap.CompressionRatio",
578        swap_info_.orig_data_size / swap_info_.compr_data_size,
579        1, 20, 20);
580  }
581}
582
583#endif
584