Add initial Blink-side support for the Screen Orientation API

public/web/WebViewClient.h

Index: public/web/WebViewClient.h
diff --git a/public/web/WebViewClient.h b/public/web/WebViewClient.h
index f1aa9f7066cabb2558ff1d496f5c1cb8cf094a8b..9634af9adaf37999c7e50cb1359a82c468a78c22 100644
--- a/public/web/WebViewClient.h
+++ b/public/web/WebViewClient.h
@@ -71,6 +71,7 @@ class WebMIDIClient;
 class WebNode;
 class WebNotificationPresenter;
 class WebRange;
+class WebScreenOrientationClient;
 class WebSpeechInputController;
 class WebSpeechInputListener;
 class WebSpeechRecognizer;
@@ -333,6 +334,11 @@ public:
     // Access the embedder API for (non-client-based) geolocation services.
     virtual WebGeolocationService* geolocationService() { return 0; }
 
+    // Screen Orientation --------------------------------------------------
+
+    // Access the embedder API for (client-based) screen orientation client.
+    virtual WebScreenOrientationClient* screenOrientationClient() { return 0; }
+
     // Speech --------------------------------------------------------------
 
     // Access the embedder API for speech input services.