Fix remaining cc files to compile with Clang

cc/HeadsUpDisplayLayerChromium.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 
 #ifndef HeadsUpDisplayLayerChromium_h
 #define HeadsUpDisplayLayerChromium_h
 
 #include "CCFontAtlas.h"
 #include "IntSize.h"
 #include "LayerChromium.h"
 
 namespace cc {
 
 class HeadsUpDisplayLayerChromium : public LayerChromium {
 public:
     static PassRefPtr<HeadsUpDisplayLayerChromium> create();
     virtual ~HeadsUpDisplayLayerChromium();
 
     virtual void update(CCTextureUpdateQueue&, const CCOcclusionTracker*, CCRenderingStats&) OVERRIDE;
-    virtual bool drawsContent() const OVERRIDE { return true; }
+    virtual bool drawsContent() const OVERRIDE;
 
     void setFontAtlas(PassOwnPtr<CCFontAtlas>);
 
     virtual PassOwnPtr<CCLayerImpl> createCCLayerImpl() OVERRIDE;
     virtual void pushPropertiesTo(CCLayerImpl*) OVERRIDE;
 
 protected:
     HeadsUpDisplayLayerChromium();
 
 private:
     OwnPtr<CCFontAtlas> m_fontAtlas;
 };
 
 }
 #endif