content/public/browser/browser_main_parts.h

   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:
  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_