Support sharing of ContentMain and BrowserMain code with embedded use cases (try #2).

chrome/browser/chrome_browser_main.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chrome_browser_main.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 1086 matching lines @@
 void ChromeBrowserMainParts::ToolkitInitialized() {
   for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
     chrome_extra_parts_[i]->ToolkitInitialized();
 }
 
 void ChromeBrowserMainParts::PreMainMessageLoopStart() {
   for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
     chrome_extra_parts_[i]->PreMainMessageLoopStart();
 }
 
+MessageLoop* ChromeBrowserMainParts::GetMainMessageLoop() {
+  return NULL;
+}
+
 void ChromeBrowserMainParts::PostMainMessageLoopStart() {
   for (size_t i = 0; i < chrome_extra_parts_.size(); ++i)
     chrome_extra_parts_[i]->PostMainMessageLoopStart();
 }
 
 int ChromeBrowserMainParts::PreCreateThreads() {
   result_code_ = PreCreateThreadsImpl();
   return result_code_;
 }
 
@@ skipping 816 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead";
     uma_name += pre_read == "1" ? "Enabled" : "Disabled";
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }