Make BrowserMainParts have an empty implementation to make embedding easier.

content/shell/shell_browser_main_parts.cc

Index: content/shell/shell_browser_main_parts.cc
===================================================================
--- content/shell/shell_browser_main_parts.cc	(revision 139582)
+++ content/shell/shell_browser_main_parts.cc	(working copy)
@@ -57,10 +57,6 @@
 }
 #endif
 
-int ShellBrowserMainParts::PreCreateThreads() {
-  return 0;
-}
-
 void ShellBrowserMainParts::PreEarlyInitialization() {
 #if defined(OS_ANDROID)
   // TODO(tedchoc): Setup the NetworkChangeNotifier here.
@@ -102,8 +98,4 @@
   browser_context_.reset();
 }
 
-bool ShellBrowserMainParts::MainMessageLoopRun(int* result_code) {
-  return false;
-}
-
 }  // namespace