Introduce the fallback theme engine that will be used to paint a fallback UI

Source/Platform/chromium/public/Platform.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 37 matching lines @@
 class GrContext;
 
 namespace WebKit {
 
 class WebAudioBus;
 class WebBlobRegistry;
 class WebClipboard;
 class WebCompositorSupport;
 class WebCookieJar;
 class WebDiscardableMemory;
+class WebFallbackThemeEngine;
 class WebFileSystem;
 class WebFileUtilities;
 class WebFlingAnimator;
 class WebGestureCurveTarget;
 class WebGestureCurve;
 class WebGraphicsContext3DProvider;
 class WebHyphenator;
 class WebMediaStreamCenter;
 class WebMediaStreamCenterClient;
 class WebMessagePortChannel;
@@ skipping 42 matching lines @@
 
     // Must return non-null.
     virtual WebMimeRegistry* mimeRegistry() { return 0; }
 
     // May return null if sandbox support is not necessary
     virtual WebSandboxSupport* sandboxSupport() { return 0; }
 
     // May return null on some platforms.
     virtual WebThemeEngine* themeEngine() { return 0; }
 
+    virtual WebFallbackThemeEngine* fallbackThemeEngine() { return 0; }
+
     // Must return non-null.
     virtual WebHyphenator* hyphenator() { return 0; }
 
     // May return null.
     virtual WebSpeechSynthesizer* createSpeechSynthesizer(WebSpeechSynthesizerClient*) { return 0; }
 
     // Audio --------------------------------------------------------------
 
     virtual double audioHardwareSampleRate() { return 0; }
     virtual size_t audioHardwareBufferSize() { return 0; }
@@ skipping 387 matching lines @@
     virtual void didStartWorkerRunLoop(const WebWorkerRunLoop&) { }
     virtual void didStopWorkerRunLoop(const WebWorkerRunLoop&) { }
 
 protected:
     virtual ~Platform() { }
 };
 
 } // namespace WebKit
 
 #endif