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/callback.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. MessageLoopCurrentForUI::Get()->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 |Pre/Post...()| methods in a embedder's platform-specific 41 // override (e.g., ChromeBrowserMainPartsWin::PreMainMessageLoopStart()); do 42 // this if the code is unique to an embedder and platform type. Or (2) 43 // execute it from one of the "stages" (e.g., 44 // |BrowserMainLoop::EarlyInitialization()|) and provide platform-specific 45 // implementations of your code (in a virtual method); do this if you need to 46 // provide different implementations across most/all platforms. 47 // - Unless your new code is just one or two lines, put it into a separate 48 // method with a well-defined purpose. (Likewise, if you're adding to an 49 // existing chunk which makes it longer than one or two lines, please move 50 // the code out into a separate method.) 51 // 52 class CONTENT_EXPORT BrowserMainParts { 53 public: BrowserMainParts()54 BrowserMainParts() {} ~BrowserMainParts()55 virtual ~BrowserMainParts() {} 56 57 // A return value other than RESULT_CODE_NORMAL_EXIT indicates error and is 58 // used as the exit status. 59 virtual int PreEarlyInitialization(); 60 PostEarlyInitialization()61 virtual void PostEarlyInitialization() {} 62 PreMainMessageLoopStart()63 virtual void PreMainMessageLoopStart() {} 64 PostMainMessageLoopStart()65 virtual void PostMainMessageLoopStart() {} 66 67 // Allows an embedder to do any extra toolkit initialization. ToolkitInitialized()68 virtual void ToolkitInitialized() {} 69 70 // Called just before any child threads owned by the content 71 // framework are created. 72 // 73 // The main message loop has been started at this point (but has not 74 // been run), and the toolkit has been initialized. Returns the error code 75 // (or 0 if no error). 76 virtual int PreCreateThreads(); 77 78 // This is called right after all child threads owned by the content framework 79 // are created. PostCreateThreads()80 virtual void PostCreateThreads() {} 81 82 // This is called just before the main message loop is run. The 83 // various browser threads have all been created at this point PreMainMessageLoopRun()84 virtual void PreMainMessageLoopRun() {} 85 86 // Returns true if the message loop was run, false otherwise. 87 // If this returns false, the default implementation will be run. 88 // May set |result_code|, which will be returned by |BrowserMain()|. 89 virtual bool MainMessageLoopRun(int* result_code); 90 91 // Provides an embedder with a Closure which will quit the default main 92 // message loop. This is call only if MainMessageLoopRun returns false. PreDefaultMainMessageLoopRun(base::OnceClosure quit_closure)93 virtual void PreDefaultMainMessageLoopRun(base::OnceClosure quit_closure) {} 94 95 // This happens after the main message loop has stopped, but before 96 // threads are stopped. PostMainMessageLoopRun()97 virtual void PostMainMessageLoopRun() {} 98 99 // Called as the very last part of shutdown, after threads have been 100 // stopped and destroyed. PostDestroyThreads()101 virtual void PostDestroyThreads() {} 102 }; 103 104 } // namespace content 105 106 #endif // CONTENT_PUBLIC_BROWSER_BROWSER_MAIN_PARTS_H_ 107