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#ifndef CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
6#define CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
7
8#include "base/basictypes.h"
9#include "content/common/content_export.h"
10
11namespace content {
12
13// This class contains different "stages" to be executed by |BrowserMain()|,
14// Each stage is represented by a single BrowserMainParts method, called from
15// the corresponding method in |BrowserMainLoop| (e.g., EarlyInitialization())
16// which does the following:
17//  - calls a method (e.g., "PreEarlyInitialization()") which implements
18//    platform / tookit specific code for that stage.
19//  - calls various methods for things common to all platforms (for that stage).
20//  - calls a method (e.g., "PostEarlyInitialization()") for platform-specific
21//    code to be called after the common code.
22//
23// Stages:
24//  - EarlyInitialization: things which should be done as soon as possible on
25//    program start (such as setting up signal handlers) and things to be done
26//    at some generic time before the start of the main message loop.
27//  - MainMessageLoopStart: things beginning with the start of the main message
28//    loop and ending with initialization of the main thread; platform-specific
29//    things which should be done immediately before the start of the main
30//    message loop should go in |PreMainMessageLoopStart()|.
31//  - RunMainMessageLoopParts:  things to be done before and after invoking the
32//    main message loop run method (e.g. MessageLoopForUI::current()->Run()).
33//
34// How to add stuff (to existing parts):
35//  - Figure out when your new code should be executed. What must happen
36//    before/after your code is executed? Are there performance reasons for
37//    running your code at a particular time? Document these things!
38//  - Split out any platform-specific bits. Please avoid #ifdefs it at all
39//    possible. You have two choices for platform-specific code: (1) Execute it
40//    from one of the platform-specific |Pre/Post...()| methods; do this if the
41//    code is unique to a platform type. Or (2) execute it from one of the
42//    "parts" (e.g., |EarlyInitialization()|) and provide platform-specific
43//    implementations of your code (in a virtual method); do this if you need to
44//    provide different implementations across most/all platforms.
45//  - Unless your new code is just one or two lines, put it into a separate
46//    method with a well-defined purpose. (Likewise, if you're adding to an
47//    existing chunk which makes it longer than one or two lines, please move
48//    the code out into a separate method.)
49//
50class CONTENT_EXPORT BrowserMainParts {
51 public:
52  BrowserMainParts() {}
53  virtual ~BrowserMainParts() {}
54
55  virtual void PreEarlyInitialization() {}
56
57  virtual void PostEarlyInitialization() {}
58
59  virtual void PreMainMessageLoopStart() {}
60
61  virtual void PostMainMessageLoopStart() {}
62
63  // Allows an embedder to do any extra toolkit initialization.
64  virtual void ToolkitInitialized() {}
65
66  // Called just before any child threads owned by the content
67  // framework are created.
68  //
69  // The main message loop has been started at this point (but has not
70  // been run), and the toolkit has been initialized. Returns the error code
71  // (or 0 if no error).
72  virtual int PreCreateThreads();
73
74  // This is called just before the main message loop is run.  The
75  // various browser threads have all been created at this point
76  virtual void PreMainMessageLoopRun() {}
77
78  // Returns true if the message loop was run, false otherwise.
79  // If this returns false, the default implementation will be run.
80  // May set |result_code|, which will be returned by |BrowserMain()|.
81  virtual bool MainMessageLoopRun(int* result_code);
82
83  // This happens after the main message loop has stopped, but before
84  // threads are stopped.
85  virtual void PostMainMessageLoopRun() {}
86
87  // Called as the very last part of shutdown, after threads have been
88  // stopped and destroyed.
89  virtual void PostDestroyThreads() {}
90};
91
92}  // namespace content
93
94#endif  // CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
95