Run the later parts of startup as UI thread tasks

content/public/app/content_main_delegate.h

Index: content/public/app/content_main_delegate.h
diff --git a/content/public/app/content_main_delegate.h b/content/public/app/content_main_delegate.h
index 9b94b98d46c8a38886cfa2774040724c104afc2f..8919304a66bdd44c309704b8ff139c3b1425a1b8 100644
--- a/content/public/app/content_main_delegate.h
+++ b/content/public/app/content_main_delegate.h
@@ -9,6 +9,7 @@
 
 #include "build/build_config.h"
 #include "content/common/content_export.h"
+#include "content/public/common/startup_task_runner.h"
 
 namespace content {
 
@@ -21,6 +22,7 @@ struct MainFunctionParams;
 
 class CONTENT_EXPORT ContentMainDelegate {
  public:
+  ContentMainDelegate() {}
   virtual ~ContentMainDelegate() {}
 
   // Tells the embedder that the absolute basic startup has been done, i.e.
@@ -46,6 +48,17 @@ class CONTENT_EXPORT ContentMainDelegate {
   // Called right before the process exits.
   virtual void ProcessExiting(const std::string& process_type) {}
 
+  // Call with true to allow the creation of a sequence of UI thread tasks to
+  // initialize the content layer. If not called, or called with false, content
+  // layer initialization must be completed in a single UI task.
+  // If called with true it is an implementation choice whether initialization
+  // requires multiple UI thread tasks.
+  virtual void EnableIncrementalStartup(bool enable) {};
+
+  // Set an observer to inform higher layers of startup progress
+  virtual void SetStartupObserver(
+      scoped_ptr<StartupTaskRunner::Observer> observer);
+
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   // Returns true if the process registers with the system monitor, so that we
   // can allocate an IO port for it before the sandbox is initialized. Embedders
@@ -82,6 +95,11 @@ class CONTENT_EXPORT ContentMainDelegate {
   virtual ContentPluginClient* CreateContentPluginClient();
   virtual ContentRendererClient* CreateContentRendererClient();
   virtual ContentUtilityClient* CreateContentUtilityClient();
+
+  StartupTaskRunner::Observer* GetStartupObserver();
+
+ private:
+  scoped_ptr<StartupTaskRunner::Observer> startup_observer_;
 };
 
 }  // namespace content