Fixes a bug when the framebuffer is cleared with invalid scissor rect

cc/direct_renderer.h

Index: cc/direct_renderer.h
diff --git a/cc/direct_renderer.h b/cc/direct_renderer.h
index 42699ed32942bd2995c24d8225c495d475fb5d3a..6ac64b2a2c0383ae2793641d5b82ac34e9d447f1 100644
--- a/cc/direct_renderer.h
+++ b/cc/direct_renderer.h
@@ -58,15 +58,20 @@ protected:
         bool isComplete() const { return m_isComplete; }
         void setIsComplete(bool isComplete) { m_isComplete = isComplete; }
 
+        bool needsFullClear() const { return m_needsFullClear; }
+        void setNeedsFullClear(bool fullClear) { m_needsFullClear = fullClear; }
+
     protected:
         explicit CachedResource(ResourceProvider* resourceProvider)
             : ScopedResource(resourceProvider)
             , m_isComplete(false)
+            , m_needsFullClear(false)
         {
         }
 
     private:
         bool m_isComplete;
+        bool m_needsFullClear;
 
         DISALLOW_COPY_AND_ASSIGN(CachedResource);
     };
@@ -90,7 +95,7 @@ protected:
     virtual bool bindFramebufferToTexture(DrawingFrame&, const ScopedResource*, const gfx::Rect& framebufferRect) = 0;
     virtual void setDrawViewportSize(const gfx::Size&) = 0;
     virtual void setScissorTestRect(const gfx::Rect& scissorRect) = 0;
-    virtual void clearFramebuffer(DrawingFrame&) = 0;
+    virtual void clearFramebuffer(DrawingFrame&, bool) = 0;
     virtual void drawQuad(DrawingFrame&, const DrawQuad*) = 0;
     virtual void beginDrawingFrame(DrawingFrame&) = 0;
     virtual void finishDrawingFrame(DrawingFrame&) = 0;