Remove synchronous compositeAndReadback() from WebLayerTreeView.

public/platform/WebLayerTreeView.h

Index: public/platform/WebLayerTreeView.h
diff --git a/public/platform/WebLayerTreeView.h b/public/platform/WebLayerTreeView.h
index 5af3f8d04ad0a8e64488a73f090ec6a701483f72..f2b7c5eb7e81c86df91034f4fc15f3b941a7d56d 100644
--- a/public/platform/WebLayerTreeView.h
+++ b/public/platform/WebLayerTreeView.h
@@ -107,14 +107,6 @@ public:
     // Relays the end of a fling animation.
     virtual void didStopFlinging() { }
 
-    // Composites and attempts to read back the result into the provided
-    // buffer. If it wasn't possible, e.g. due to context lost, will return
-    // false. Pixel format is 32bit (RGBA), and the provided buffer must be
-    // large enough contain viewportSize().width() * viewportSize().height()
-    // pixels. The WebLayerTreeView does not assume ownership of the buffer.
-    // The buffer is not modified if the false is returned.
-    virtual bool compositeAndReadback(void *pixels, const WebRect&) = 0;
-
     // The caller is responsible for keeping the WebCompositeAndReadbackAsyncCallback
     // object alive until it is called.
     virtual void compositeAndReadbackAsync(WebCompositeAndReadbackAsyncCallback*) { }