cc: Replace Region with SimpleEnclosedRegion for occlusion tracking

cc/resources/layer_tiling_data.h

Index: cc/resources/layer_tiling_data.h
diff --git a/cc/resources/layer_tiling_data.h b/cc/resources/layer_tiling_data.h
index 32fec4e0479ae547071df8a1d63cff7841a9ae04..dd0d43a949dcc4aa60e29371143eb1fbf2ef2d3a 100644
--- a/cc/resources/layer_tiling_data.h
+++ b/cc/resources/layer_tiling_data.h
@@ -12,7 +12,7 @@
 #include "base/containers/scoped_ptr_hash_map.h"
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
-#include "cc/base/region.h"
+#include "cc/base/simple_enclosed_region.h"
 #include "cc/base/tiling_data.h"
 #include "ui/gfx/rect.h"
 
@@ -91,7 +91,7 @@ class CC_EXPORT LayerTilingData {
                                 int* bottom) const;
   gfx::Rect TileRect(const Tile* tile) const;
 
-  Region OpaqueRegionInContentRect(const gfx::Rect& rect) const;
+  SimpleEnclosedRegion OpaqueRegionInContentRect(const gfx::Rect& rect) const;
 
   void reset() { tiles_.clear(); }