Add IDL and initial Blink API for Background Sync

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index c30e8d260c924fd0f1bf3ef4b6b7e84bfa786c7f..060c5e3518a1de33e37afc26de047f87a9bcebf9 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -101,6 +101,7 @@ class WebSocketHandle;
 class WebSpeechSynthesizer;
 class WebSpeechSynthesizerClient;
 class WebStorageNamespace;
+class WebSyncProvider;
 struct WebFloatPoint;
 class WebThemeEngine;
 class WebThread;
@@ -661,11 +662,16 @@ public:
 
     virtual WebNavigatorConnectProvider* navigatorConnectProvider() { return 0; }
 
+

[jochen (gone - plz use gerrit), 2015/03/17 12:25:35]

unrelated

[iclelland, 2015/03/19 13:13:42]

Done.

     // Permissions --------------------------------------------------------
 
     virtual WebPermissionClient* permissionClient() { return 0; }
 
 
+    // Background Sync API------------------------------------------------------------
+
+    virtual WebSyncProvider* backgroundSyncProvider() { return 0; }
+
 protected:
     BLINK_PLATFORM_EXPORT Platform();
     virtual ~Platform() { }