cc: Define Region::Contains() to be A contains B if all points in B are also in A.

cc/occlusion_tracker.cc

 // 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.
 
 #include "config.h"
 
 #include "cc/occlusion_tracker.h"
 
 #include <algorithm>
 
@@ skipping 296 matching lines @@
         gfx::Rect clipRectInScreen = gfx::IntersectRects(m_rootTargetRect, gfx::ToEnclosedRect(clipQuadInScreen.BoundingBox()));
         addOcclusionBehindLayer<LayerType>(m_stack.back().occlusionInScreen, layer, layer->screenSpaceTransform(), opaqueContents, clipRectInScreen, m_minimumTrackingSize, m_occludingScreenSpaceRects);
     }
 }
 
 static inline bool testContentRectOccluded(const gfx::Rect& contentRect, const WebTransformationMatrix& contentSpaceTransform, const gfx::Rect& clipRectInTarget, const Region& occlusion)
 {
     gfx::RectF transformedRect = MathUtil::mapClippedRect(contentSpaceTransform, gfx::RectF(contentRect));
     // Take the gfx::ToEnclosingRect, as we want to include partial pixels in the test.
     gfx::Rect targetRect = gfx::IntersectRects(gfx::ToEnclosingRect(transformedRect), clipRectInTarget);
-    return targetRect.IsEmpty() || occlusion.Contains(targetRect);
+    return occlusion.Contains(targetRect);
 }
 
 template<typename LayerType, typename RenderSurfaceType>
 bool OcclusionTrackerBase<LayerType, RenderSurfaceType>::occluded(const LayerType* renderTarget, const gfx::Rect& contentRect, const WebKit::WebTransformationMatrix& drawTransform, bool implDrawTransformIsUnknown, const gfx::Rect& clippedRectInTarget, bool* hasOcclusionFromOutsideTargetSurface) const
 {
     if (hasOcclusionFromOutsideTargetSurface)
         *hasOcclusionFromOutsideTargetSurface = false;
 
     DCHECK(!m_stack.empty());
     if (m_stack.empty())
@@ skipping 130 matching lines @@
     // FIXME: we could remove this helper function, but unit tests currently override this
     //        function, and they need to be verified/adjusted before this can be removed.
     return layer->drawableContentRect();
 }
 
 // Instantiate (and export) templates here for the linker.
 template class OcclusionTrackerBase<Layer, RenderSurface>;
 template class OcclusionTrackerBase<LayerImpl, RenderSurfaceImpl>;
 
 }  // namespace cc