[Android WebView] Implement initial settings and callback support for Service Workers.

android_webview/browser/aw_contents_io_thread_client.h

Index: android_webview/browser/aw_contents_io_thread_client.h
diff --git a/android_webview/browser/aw_contents_io_thread_client.h b/android_webview/browser/aw_contents_io_thread_client.h
index 16ad5dd86e3802eb1e41b513255c49e00be1f899..19310066720f794de81e8bfababa70a7d4bf13be 100644
--- a/android_webview/browser/aw_contents_io_thread_client.h
+++ b/android_webview/browser/aw_contents_io_thread_client.h
@@ -66,6 +66,10 @@ class AwContentsIoThreadClient {
   static scoped_ptr<AwContentsIoThreadClient> FromID(int render_process_id,
                                                      int render_frame_id);
 
+  // Returns the global thread client for service worker related callbacks.
+  // An empty scoped_ptr is a valid return value.
+  static scoped_ptr<AwContentsIoThreadClient> GetServiceWorkerIoThreadClient();
+
   // Called on the IO thread when a subframe is created.
   static void SubFrameCreated(int render_process_id,
                               int parent_render_frame_id,