cc: Don't subtract transparent overlay from damage.

cc/output/overlay_unittest.cc

 // Copyright 2014 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 <stddef.h>
 
 #include <utility>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
@@ skipping 738 matching lines @@
   output_surface_plane.use_output_surface_for_resource = true;
   output_surface_plane.overlay_handled = true;
   candidate_list.push_back(output_surface_plane);
 
   RenderPassFilterList render_pass_filters;
   RenderPassFilterList render_pass_background_filters;
   overlay_processor_->ProcessForOverlays(
       resource_provider_.get(), pass.get(), render_pass_filters,
       render_pass_background_filters, &candidate_list, nullptr, nullptr,
       &damage_rect_, &content_bounds_);
-  DCHECK(damage_rect_.IsEmpty());
+  EXPECT_TRUE(damage_rect_.IsEmpty());
 }
 
 TEST_F(SingleOverlayOnTopTest, NoCandidates) {
   std::unique_ptr<RenderPass> pass = CreateRenderPass();
   CreateFullscreenOpaqueQuad(resource_provider_.get(),
                              pass->shared_quad_state_list.back(), pass.get());
   CreateFullscreenOpaqueQuad(resource_provider_.get(),
                              pass->shared_quad_state_list.back(), pass.get());
 
   RenderPassList pass_list;
@@ skipping 72 matching lines @@
   TextureDrawQuad* quad =
       CreateFullscreenCandidateQuad(resource_provider_.get(),
                                     pass->shared_quad_state_list.back(),
                                     pass.get());
   quad->needs_blending = true;
   quad->opaque_rect = gfx::Rect(0, 0, 0, 0);
 
   OverlayCandidateList candidate_list;
   RenderPassFilterList render_pass_filters;
   RenderPassFilterList render_pass_background_filters;
+  damage_rect_ = quad->rect;
   overlay_processor_->ProcessForOverlays(
       resource_provider_.get(), pass.get(), render_pass_filters,
       render_pass_background_filters, &candidate_list, nullptr, nullptr,
       &damage_rect_, &content_bounds_);
   EXPECT_EQ(1U, candidate_list.size());
+  EXPECT_FALSE(damage_rect_.IsEmpty());
 }
 
 TEST_F(SingleOverlayOnTopTest, RejectBackgroundColor) {
   std::unique_ptr<RenderPass> pass = CreateRenderPass();
   TextureDrawQuad* quad =
       CreateFullscreenCandidateQuad(resource_provider_.get(),
                                     pass->shared_quad_state_list.back(),
                                     pass.get());
   quad->background_color = SK_ColorBLACK;
 
@@ skipping 1732 matching lines @@
                  kOverlayRect, render_pass_id_, 2, gfx::RectF(), gfx::Size(),
                  gfx::Vector2dF(1, 1), gfx::PointF(), gfx::RectF());
   }
 
   ProcessForOverlays();
   EXPECT_EQ(0U, ca_layer_list_.size());
 }
 
 }  // namespace
 }  // namespace cc