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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 
11 namespace 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 //
50 class CONTENT_EXPORT BrowserMainParts {
51  public:
BrowserMainParts()52   BrowserMainParts() {}
~BrowserMainParts()53   virtual ~BrowserMainParts() {}
54 
PreEarlyInitialization()55   virtual void PreEarlyInitialization() {}
56 
PostEarlyInitialization()57   virtual void PostEarlyInitialization() {}
58 
PreMainMessageLoopStart()59   virtual void PreMainMessageLoopStart() {}
60 
PostMainMessageLoopStart()61   virtual void PostMainMessageLoopStart() {}
62 
63   // Allows an embedder to do any extra toolkit initialization.
ToolkitInitialized()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
PreMainMessageLoopRun()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.
PostMainMessageLoopRun()85   virtual void PostMainMessageLoopRun() {}
86 
87   // Called as the very last part of shutdown, after threads have been
88   // stopped and destroyed.
PostDestroyThreads()89   virtual void PostDestroyThreads() {}
90 };
91 
92 }  // namespace content
93 
94 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_
95