SkCanvas::clear() should call down to devices even when the clip is empty.

src/core/SkCanvas.cpp

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkCanvasDrawable.h"
 #include "SkCanvasPriv.h"
@@ skipping 1684 matching lines @@
     SkASSERT(outer.getBounds().contains(inner.getBounds()));
 
     this->onDrawDRRect(outer, inner, paint);
 }
 
 //////////////////////////////////////////////////////////////////////////////
 //  These are the virtual drawing methods
 //////////////////////////////////////////////////////////////////////////////
 
 void SkCanvas::clear(SkColor color) {
-    SkDrawIter  iter(this);
+    SkDrawIter  iter(this, false/*clear can affect empty clips*/);
     this->predrawNotify();
     while (iter.next()) {
         iter.fDevice->clear(color);
     }
 }
 
 void SkCanvas::onDiscard() {
     if (fSurfaceBase) {
         fSurfaceBase->aboutToDraw(SkSurface::kDiscard_ContentChangeMode);
     }
@@ skipping 863 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }