cc: Replace Region with SimpleEnclosedRegion for occlusion tracking

cc/layers/layer_impl.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 "cc/layers/layer_impl.h"
 
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/json/json_reader.h"
 #include "base/strings/stringprintf.h"
 #include "cc/animation/animation_registrar.h"
 #include "cc/animation/scrollbar_animation_controller.h"
 #include "cc/base/math_util.h"
+#include "cc/base/simple_enclosed_region.h"
 #include "cc/debug/debug_colors.h"
 #include "cc/debug/layer_tree_debug_state.h"
 #include "cc/debug/micro_benchmark_impl.h"
 #include "cc/debug/traced_value.h"
 #include "cc/input/layer_scroll_offset_delegate.h"
 #include "cc/layers/layer_utils.h"
 #include "cc/layers/painted_scrollbar_layer_impl.h"
 #include "cc/output/copy_output_request.h"
 #include "cc/quads/debug_border_draw_quad.h"
 #include "cc/trees/layer_tree_host_common.h"
@@ skipping 1116 matching lines @@
 }
 
 void LayerImpl::SetDoubleSided(bool double_sided) {
   if (double_sided_ == double_sided)
     return;
 
   double_sided_ = double_sided;
   NoteLayerPropertyChangedForSubtree();
 }
 
-Region LayerImpl::VisibleContentOpaqueRegion() const {
+SimpleEnclosedRegion LayerImpl::VisibleContentOpaqueRegion() const {
   if (contents_opaque())
-    return visible_content_rect();
-  return Region();
+    return SimpleEnclosedRegion(visible_content_rect());
+  return SimpleEnclosedRegion();
 }
 
 void LayerImpl::DidBeginTracing() {}
 
 void LayerImpl::ReleaseResources() {}
 
 gfx::Vector2d LayerImpl::MaxScrollOffset() const {
   if (!scroll_clip_layer_ || bounds().IsEmpty())
     return gfx::Vector2d();
 
@@ skipping 371 matching lines @@
 }
 
 void LayerImpl::NotifyAnimationFinished(
     base::TimeTicks monotonic_time,
     Animation::TargetProperty target_property) {
   if (target_property == Animation::ScrollOffset)
     layer_tree_impl_->InputScrollAnimationFinished();
 }
 
 }  // namespace cc