Introduce chrome.shell.createWindow stub API for app_shell

chrome/renderer/extensions/dispatcher.cc

Index: chrome/renderer/extensions/dispatcher.cc
diff --git a/chrome/renderer/extensions/dispatcher.cc b/chrome/renderer/extensions/dispatcher.cc
index cd5f4433d0608d885e397b9fb60787c86fa605a3..59311fdfdd2f3d4f895d8a33320abfc437aeaa97 100644
--- a/chrome/renderer/extensions/dispatcher.cc
+++ b/chrome/renderer/extensions/dispatcher.cc
@@ -72,6 +72,7 @@
 #include "extensions/renderer/document_custom_bindings.h"
 #include "extensions/renderer/event_bindings.h"
 #include "extensions/renderer/extension_groups.h"
+#include "extensions/renderer/extensions_renderer_client.h"
 #include "extensions/renderer/file_system_natives.h"
 #include "extensions/renderer/i18n_custom_bindings.h"
 #include "extensions/renderer/id_generator_custom_bindings.h"
@@ -475,6 +476,8 @@ Dispatcher::Dispatcher()
   user_script_slave_.reset(new UserScriptSlave(&extensions_));
   request_sender_.reset(new RequestSender(this));
   PopulateSourceMap();
+  // Register JS sources from the extensions module embedder.
+  ExtensionsRendererClient::Get()->PopulateSourceMap(&source_map_);
   PopulateLazyBindingsMap();
 }
 
@@ -1161,8 +1164,13 @@ void Dispatcher::DidCreateScriptContext(
   ModuleSystem::NativesEnabledScope natives_enabled_scope(
       module_system);
 
+  // Register the core extensions native handlers.
   RegisterNativeHandlers(module_system, context);
 
+  // Register native handlers from the extensions embedder.
+  ExtensionsRendererClient::Get()->RegisterNativeHandlers(module_system,
+                                                          context);
+
   module_system->RegisterNativeHandler("chrome",
       scoped_ptr<NativeHandler>(new ChromeNativeHandler(context)));
   module_system->RegisterNativeHandler("print",