render_frame_proxy_host.h revision a02191e04bc25c4935f804f2c080ae28663d096d 
1// Copyright 2014 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#ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
6#define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
7
8#include "base/memory/scoped_ptr.h"
9#include "content/browser/frame_host/render_frame_host_impl.h"
10#include "content/browser/site_instance_impl.h"
11
12class RenderProcessHost;
13class RenderFrameHostImpl;
14class RenderViewHostImpl;
15
16namespace content {
17
18// When a page's frames are rendered by multiple processes, each renderer has a
19// full copy of the frame tree. It has full RenderFrames for the frames it is
20// responsible for rendering and placeholder objects (i.e., RenderFrameProxies)
21// for frames rendered by other processes.
22//
23// This class is the browser-side host object for the placeholder. Each node in
24// the frame tree has a RenderFrameHost for the active SiteInstance and a set
25// of RenderFrameProxyHost objects - one for all other SiteInstances with
26// references to this frame. The proxies allow us to keep existing window
27// references valid over cross-process navigations and route cross-site
28// asynchronous JavaScript calls, such as postMessage.
29//
30// For now, RenderFrameProxyHost is created when a RenderFrameHost is swapped
31// out and acts just as a wrapper. If a RenderFrameHost can be deleted, no
32// proxy object is created. It is destroyed when the RenderFrameHost is swapped
33// back in or is no longer referenced and is therefore deleted.
34//
35// Long term, RenderFrameProxyHost will be created whenever a cross-site
36// navigation occurs and a reference to the frame navigating needs to be kept
37// alive. A RenderFrameProxyHost and a RenderFrameHost for the same SiteInstance
38// can exist at the same time, but only one will be "active" at a time.
39// There are two cases where the two objects will coexist:
40// * When navigating cross-process and there is already a RenderFrameProxyHost
41// for the new SiteInstance. A pending RenderFrameHost is created, but it is
42// not used until it commits. At that point, RenderFrameHostManager transitions
43// the pending RenderFrameHost to the active one and deletes the proxy.
44// * When navigating cross-process and the existing document has an unload
45// event handler. When the new navigation commits, RenderFrameHostManager
46// creates a RenderFrameProxyHost for the old SiteInstance and uses it going
47// forward. It also instructs the RenderFrameHost to run the unload event
48// handler and is kept alive for the duration. Once the event handling is
49// complete, the RenderFrameHost is deleted.
50class RenderFrameProxyHost {
51 public:
52  explicit RenderFrameProxyHost(
53       scoped_ptr<RenderFrameHostImpl> render_frame_host);
54  ~RenderFrameProxyHost();
55
56  RenderProcessHost* GetProcess() {
57    return render_frame_host_->GetProcess();
58  }
59
60  SiteInstance* GetSiteInstance() {
61    return site_instance_.get();
62  }
63
64  // TODO(nasko): The following methods should be removed when swapping out
65  // of RenderFrameHosts is no longer used.
66  RenderFrameHostImpl* render_frame_host() {
67    return render_frame_host_.get();
68  }
69  RenderViewHostImpl* render_view_host() {
70    return render_frame_host_->render_view_host();
71  }
72  scoped_ptr<RenderFrameHostImpl> PassFrameHost() {
73    return render_frame_host_.Pass();
74  }
75
76 private:
77  scoped_refptr<SiteInstance> site_instance_;
78
79  // TODO(nasko): For now, hide the RenderFrameHost inside the proxy, but remove
80  // it once we have all the code support for proper proxy objects.
81  scoped_ptr<RenderFrameHostImpl> render_frame_host_;
82
83  DISALLOW_COPY_AND_ASSIGN(RenderFrameProxyHost);
84};
85
86}  // namespace
87
88#endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_PROXY_HOST_H_
89