cc: Make PrepareToDraw return an enum for why it aborts

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 242 matching lines @@
     layer->SetDrawsContent(true);
     layer->SetBounds(size);
     layer->SetContentBounds(size);
     layer->SetMaxScrollOffset(gfx::Vector2d(size.width() * 2,
                                             size.height() * 2));
     return layer.Pass();
   }
 
   void DrawFrame() {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   void pinch_zoom_pan_viewport_forces_commit_redraw(float device_scale_factor);
   void pinch_zoom_pan_viewport_test(float device_scale_factor);
   void pinch_zoom_pan_viewport_and_scroll_test(float device_scale_factor);
   void pinch_zoom_pan_viewport_and_scroll_boundary_test(
       float device_scale_factor);
 
@@ skipping 1202 matching lines @@
       DidDrawCheckLayer::Create(host_impl_->active_tree(), 1));
   DidDrawCheckLayer* root = static_cast<DidDrawCheckLayer*>(
       host_impl_->active_tree()->root_layer());
 
   root->AddChild(DidDrawCheckLayer::Create(host_impl_->active_tree(), 2));
   DidDrawCheckLayer* layer =
       static_cast<DidDrawCheckLayer*>(root->children()[0]);
 
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect(10, 10)));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect(10, 10)));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
 
     EXPECT_TRUE(layer->will_draw_called());
     EXPECT_TRUE(layer->append_quads_called());
     EXPECT_TRUE(layer->did_draw_called());
   }
 
   {
     LayerTreeHostImpl::FrameData frame;
 
     layer->set_will_draw_returns_false();
     layer->ClearDidDrawCheck();
 
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect(10, 10)));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect(10, 10)));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
 
     EXPECT_TRUE(layer->will_draw_called());
     EXPECT_FALSE(layer->append_quads_called());
     EXPECT_FALSE(layer->did_draw_called());
   }
 }
 
 TEST_F(LayerTreeHostImplTest, DidDrawNotCalledOnHiddenLayer) {
@@ skipping 11 matching lines @@
   // Ensure visible_content_rect for layer is empty.
   layer->SetPosition(gfx::PointF(100.f, 100.f));
   layer->SetBounds(gfx::Size(10, 10));
   layer->SetContentBounds(gfx::Size(10, 10));
 
   LayerTreeHostImpl::FrameData frame;
 
   EXPECT_FALSE(layer->will_draw_called());
   EXPECT_FALSE(layer->did_draw_called());
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_FALSE(layer->will_draw_called());
   EXPECT_FALSE(layer->did_draw_called());
 
   EXPECT_TRUE(layer->visible_content_rect().IsEmpty());
 
   // Ensure visible_content_rect for layer is not empty
   layer->SetPosition(gfx::PointF());
 
   EXPECT_FALSE(layer->will_draw_called());
   EXPECT_FALSE(layer->did_draw_called());
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_TRUE(layer->will_draw_called());
   EXPECT_TRUE(layer->did_draw_called());
 
   EXPECT_FALSE(layer->visible_content_rect().IsEmpty());
 }
 
 TEST_F(LayerTreeHostImplTest, WillDrawNotCalledOnOccludedLayer) {
@@ skipping 18 matching lines @@
   top_layer->SetContentBounds(big_size);
   top_layer->SetContentsOpaque(true);
 
   LayerTreeHostImpl::FrameData frame;
 
   EXPECT_FALSE(occluded_layer->will_draw_called());
   EXPECT_FALSE(occluded_layer->did_draw_called());
   EXPECT_FALSE(top_layer->will_draw_called());
   EXPECT_FALSE(top_layer->did_draw_called());
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_FALSE(occluded_layer->will_draw_called());
   EXPECT_FALSE(occluded_layer->did_draw_called());
   EXPECT_TRUE(top_layer->will_draw_called());
   EXPECT_TRUE(top_layer->did_draw_called());
 }
 
 TEST_F(LayerTreeHostImplTest, DidDrawCalledOnAllLayers) {
@@ skipping 11 matching lines @@
       static_cast<DidDrawCheckLayer*>(layer1->children()[0]);
 
   layer1->SetOpacity(0.3f);
   layer1->SetPreserves3d(false);
 
   EXPECT_FALSE(root->did_draw_called());
   EXPECT_FALSE(layer1->did_draw_called());
   EXPECT_FALSE(layer2->did_draw_called());
 
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_TRUE(root->did_draw_called());
   EXPECT_TRUE(layer1->did_draw_called());
   EXPECT_TRUE(layer2->did_draw_called());
 
   EXPECT_NE(root->render_surface(), layer1->render_surface());
   EXPECT_TRUE(!!layer1->render_surface());
 }
@@ skipping 52 matching lines @@
   root->AddChild(
       MissingTextureAnimatingLayer::Create(host_impl_->active_tree(),
                                            2,
                                            false,
                                            false,
                                            true,
                                            host_impl_->resource_provider()));
 
   LayerTreeHostImpl::FrameData frame;
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   // When a texture is missing and we're not animating, we draw as usual with
   // checkerboarding.
   host_impl_->active_tree()->SetRootLayer(
       DidDrawCheckLayer::Create(host_impl_->active_tree(), 3));
   root =
       static_cast<DidDrawCheckLayer*>(host_impl_->active_tree()->root_layer());
   root->AddChild(
       MissingTextureAnimatingLayer::Create(host_impl_->active_tree(),
                                            4,
                                            true,
                                            false,
                                            false,
                                            host_impl_->resource_provider()));
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   // When a texture is missing and we're animating, we don't want to draw
   // anything.
   host_impl_->active_tree()->SetRootLayer(
       DidDrawCheckLayer::Create(host_impl_->active_tree(), 5));
   root =
       static_cast<DidDrawCheckLayer*>(host_impl_->active_tree()->root_layer());
   root->AddChild(
       MissingTextureAnimatingLayer::Create(host_impl_->active_tree(),
                                            6,
                                            true,
                                            false,
                                            true,
                                            host_impl_->resource_provider()));
 
-  EXPECT_FALSE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DRAW_ABORTED_CHECKERBOARD_ANIMATIONS,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   // When the layer skips draw and we're animating, we still draw the frame.
   host_impl_->active_tree()->SetRootLayer(
       DidDrawCheckLayer::Create(host_impl_->active_tree(), 7));
   root =
       static_cast<DidDrawCheckLayer*>(host_impl_->active_tree()->root_layer());
   root->AddChild(
       MissingTextureAnimatingLayer::Create(host_impl_->active_tree(),
@@ skipping 289 matching lines @@
   EXPECT_EQ(1.f, scroll->contents_scale_x());
   EXPECT_EQ(1.f, scroll->contents_scale_y());
   EXPECT_EQ(1.f, child->contents_scale_x());
   EXPECT_EQ(1.f, child->contents_scale_y());
   EXPECT_EQ(1.f, grand_child->contents_scale_x());
   EXPECT_EQ(1.f, grand_child->contents_scale_y());
 
   // Make sure all the layers are drawn with the page scale delta applied, i.e.,
   // the page scale delta on the root layer is applied hierarchically.
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_EQ(1.f, root->draw_transform().matrix().getDouble(0, 0));
   EXPECT_EQ(1.f, root->draw_transform().matrix().getDouble(1, 1));
   EXPECT_EQ(new_page_scale, scroll->draw_transform().matrix().getDouble(0, 0));
   EXPECT_EQ(new_page_scale, scroll->draw_transform().matrix().getDouble(1, 1));
   EXPECT_EQ(new_page_scale, child->draw_transform().matrix().getDouble(0, 0));
   EXPECT_EQ(new_page_scale, child->draw_transform().matrix().getDouble(1, 1));
   EXPECT_EQ(new_page_scale,
@@ skipping 795 matching lines @@
   BlendStateCheckLayer* layer1 =
       static_cast<BlendStateCheckLayer*>(root->children()[0]);
   layer1->SetPosition(gfx::PointF(2.f, 2.f));
 
   LayerTreeHostImpl::FrameData frame;
 
   // Opaque layer, drawn without blending.
   layer1->SetContentsOpaque(true);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with translucent content and painting, so drawn with blending.
   layer1->SetContentsOpaque(false);
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with translucent opacity, drawn with blending.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(0.5f);
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with translucent opacity and painting, drawn with blending.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(0.5f);
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   layer1->AddChild(
       BlendStateCheckLayer::Create(host_impl_->active_tree(),
                                    3,
                                    host_impl_->resource_provider()));
   BlendStateCheckLayer* layer2 =
       static_cast<BlendStateCheckLayer*>(layer1->children()[0]);
   layer2->SetPosition(gfx::PointF(4.f, 4.f));
 
   // 2 opaque layers, drawn without blending.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(1.f);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetContentsOpaque(true);
   layer2->SetOpacity(1.f);
   layer2->SetExpectation(false, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Parent layer with translucent content, drawn with blending.
   // Child layer with opaque content, drawn without blending.
   layer1->SetContentsOpaque(false);
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetExpectation(false, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Parent layer with translucent content but opaque painting, drawn without
   // blending.
   // Child layer with opaque content, drawn without blending.
   layer1->SetContentsOpaque(true);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetExpectation(false, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Parent layer with translucent opacity and opaque content. Since it has a
   // drawing child, it's drawn to a render surface which carries the opacity,
   // so it's itself drawn without blending.
   // Child layer with opaque content, drawn without blending (parent surface
   // carries the inherited opacity).
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(0.5f);
   layer1->SetExpectation(false, true);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetExpectation(false, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Draw again, but with child non-opaque, to make sure
   // layer1 not culled.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(1.f);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetContentsOpaque(true);
   layer2->SetOpacity(0.5f);
   layer2->SetExpectation(true, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // A second way of making the child non-opaque.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(1.f);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetContentsOpaque(false);
   layer2->SetOpacity(1.f);
   layer2->SetExpectation(true, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // And when the layer says its not opaque but is painted opaque, it is not
   // blended.
   layer1->SetContentsOpaque(true);
   layer1->SetOpacity(1.f);
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
   layer2->SetContentsOpaque(true);
   layer2->SetOpacity(1.f);
   layer2->SetExpectation(false, false);
   layer2->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   EXPECT_TRUE(layer2->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with partially opaque contents, drawn with blending.
   layer1->SetContentsOpaque(false);
   layer1->SetQuadRect(gfx::Rect(5, 5, 5, 5));
   layer1->SetQuadVisibleRect(gfx::Rect(5, 5, 5, 5));
   layer1->SetOpaqueContentRect(gfx::Rect(5, 5, 2, 5));
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with partially opaque contents partially culled, drawn with blending.
   layer1->SetContentsOpaque(false);
   layer1->SetQuadRect(gfx::Rect(5, 5, 5, 5));
   layer1->SetQuadVisibleRect(gfx::Rect(5, 5, 5, 2));
   layer1->SetOpaqueContentRect(gfx::Rect(5, 5, 2, 5));
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with partially opaque contents culled, drawn with blending.
   layer1->SetContentsOpaque(false);
   layer1->SetQuadRect(gfx::Rect(5, 5, 5, 5));
   layer1->SetQuadVisibleRect(gfx::Rect(7, 5, 3, 5));
   layer1->SetOpaqueContentRect(gfx::Rect(5, 5, 2, 5));
   layer1->SetExpectation(true, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 
   // Layer with partially opaque contents and translucent contents culled, drawn
   // without blending.
   layer1->SetContentsOpaque(false);
   layer1->SetQuadRect(gfx::Rect(5, 5, 5, 5));
   layer1->SetQuadVisibleRect(gfx::Rect(5, 5, 2, 5));
   layer1->SetOpaqueContentRect(gfx::Rect(5, 5, 2, 5));
   layer1->SetExpectation(false, false);
   layer1->SetUpdateRect(gfx::RectF(layer1->content_bounds()));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(layer1->quads_appended());
   host_impl_->DidDrawAllLayers(frame);
 }
 
 class LayerTreeHostImplViewportCoveredTest : public LayerTreeHostImplTest {
  protected:
   LayerTreeHostImplViewportCoveredTest() :
       gutter_quad_material_(DrawQuad::SOLID_COLOR),
       child_(NULL),
@@ skipping 24 matching lines @@
   // Expect no gutter rects.
   void TestLayerCoversFullViewport() {
     gfx::Rect layer_rect(viewport_size_);
     child_->SetPosition(layer_rect.origin());
     child_->SetBounds(layer_rect.size());
     child_->SetContentBounds(layer_rect.size());
     child_->SetQuadRect(gfx::Rect(layer_rect.size()));
     child_->SetQuadVisibleRect(gfx::Rect(layer_rect.size()));
 
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     ASSERT_EQ(1u, frame.render_passes.size());
 
     EXPECT_EQ(0u, CountGutterQuads(frame.render_passes[0]->quad_list));
     EXPECT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ValidateTextureDrawQuads(frame.render_passes[0]->quad_list);
 
     VerifyQuadsExactlyCoverViewport(frame.render_passes[0]->quad_list);
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Expect fullscreen gutter rect.
   void TestEmptyLayer() {
     gfx::Rect layer_rect(0, 0, 0, 0);
     child_->SetPosition(layer_rect.origin());
     child_->SetBounds(layer_rect.size());
     child_->SetContentBounds(layer_rect.size());
     child_->SetQuadRect(gfx::Rect(layer_rect.size()));
     child_->SetQuadVisibleRect(gfx::Rect(layer_rect.size()));
 
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     ASSERT_EQ(1u, frame.render_passes.size());
 
     EXPECT_EQ(1u, CountGutterQuads(frame.render_passes[0]->quad_list));
     EXPECT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ValidateTextureDrawQuads(frame.render_passes[0]->quad_list);
 
     VerifyQuadsExactlyCoverViewport(frame.render_passes[0]->quad_list);
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Expect four surrounding gutter rects.
   void TestLayerInMiddleOfViewport() {
     gfx::Rect layer_rect(500, 500, 200, 200);
     child_->SetPosition(layer_rect.origin());
     child_->SetBounds(layer_rect.size());
     child_->SetContentBounds(layer_rect.size());
     child_->SetQuadRect(gfx::Rect(layer_rect.size()));
     child_->SetQuadVisibleRect(gfx::Rect(layer_rect.size()));
 
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     ASSERT_EQ(1u, frame.render_passes.size());
 
     EXPECT_EQ(4u, CountGutterQuads(frame.render_passes[0]->quad_list));
     EXPECT_EQ(5u, frame.render_passes[0]->quad_list.size());
     ValidateTextureDrawQuads(frame.render_passes[0]->quad_list);
 
     VerifyQuadsExactlyCoverViewport(frame.render_passes[0]->quad_list);
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Expect no gutter rects.
   void TestLayerIsLargerThanViewport() {
     gfx::Rect layer_rect(viewport_size_.width() + 10,
                          viewport_size_.height() + 10);
     child_->SetPosition(layer_rect.origin());
     child_->SetBounds(layer_rect.size());
     child_->SetContentBounds(layer_rect.size());
     child_->SetQuadRect(gfx::Rect(layer_rect.size()));
     child_->SetQuadVisibleRect(gfx::Rect(layer_rect.size()));
 
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     ASSERT_EQ(1u, frame.render_passes.size());
 
     EXPECT_EQ(0u, CountGutterQuads(frame.render_passes[0]->quad_list));
     EXPECT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ValidateTextureDrawQuads(frame.render_passes[0]->quad_list);
 
     host_impl_->DidDrawAllLayers(frame);
   }
 
   virtual void DidActivatePendingTree() OVERRIDE {
@@ skipping 198 matching lines @@
   root->SetBounds(gfx::Size(10, 10));
   root->SetContentBounds(gfx::Size(10, 10));
   root->SetDrawsContent(true);
   host_impl_->active_tree()->SetRootLayer(root.Pass());
   EXPECT_FALSE(provider->TestContext3d()->reshape_called());
   provider->TestContext3d()->clear_reshape_called();
 
   LayerTreeHostImpl::FrameData frame;
   host_impl_->SetViewportSize(gfx::Size(10, 10));
   host_impl_->SetDeviceScaleFactor(1.f);
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(provider->TestContext3d()->reshape_called());
   EXPECT_EQ(provider->TestContext3d()->width(), 10);
   EXPECT_EQ(provider->TestContext3d()->height(), 10);
   EXPECT_EQ(provider->TestContext3d()->scale_factor(), 1.f);
   host_impl_->DidDrawAllLayers(frame);
   provider->TestContext3d()->clear_reshape_called();
 
   host_impl_->SetViewportSize(gfx::Size(20, 30));
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(provider->TestContext3d()->reshape_called());
   EXPECT_EQ(provider->TestContext3d()->width(), 20);
   EXPECT_EQ(provider->TestContext3d()->height(), 30);
   EXPECT_EQ(provider->TestContext3d()->scale_factor(), 1.f);
   host_impl_->DidDrawAllLayers(frame);
   provider->TestContext3d()->clear_reshape_called();
 
   host_impl_->SetDeviceScaleFactor(2.f);
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   EXPECT_TRUE(provider->TestContext3d()->reshape_called());
   EXPECT_EQ(provider->TestContext3d()->width(), 20);
   EXPECT_EQ(provider->TestContext3d()->height(), 30);
   EXPECT_EQ(provider->TestContext3d()->scale_factor(), 2.f);
   host_impl_->DidDrawAllLayers(frame);
   provider->TestContext3d()->clear_reshape_called();
 }
 
 // Make sure damage tracking propagates all the way to the graphics context,
@@ skipping 29 matching lines @@
   root->SetAnchorPoint(gfx::PointF());
   root->SetBounds(gfx::Size(500, 500));
   root->SetContentBounds(gfx::Size(500, 500));
   root->SetDrawsContent(true);
   root->AddChild(child.Pass());
   layer_tree_host_impl->active_tree()->SetRootLayer(root.Pass());
 
   LayerTreeHostImpl::FrameData frame;
 
   // First frame, the entire screen should get swapped.
-  EXPECT_TRUE(layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
   layer_tree_host_impl->DrawLayers(&frame, gfx::FrameTime::Now());
   layer_tree_host_impl->DidDrawAllLayers(frame);
   layer_tree_host_impl->SwapBuffers(frame);
   EXPECT_EQ(TestContextSupport::SWAP,
             context_provider->support()->last_swap_type());
 
   // Second frame, only the damaged area should get swapped. Damage should be
   // the union of old and new child rects.
   // expected damage rect: gfx::Rect(26, 28);
   // expected swap rect: vertically flipped, with origin at bottom left corner.
   layer_tree_host_impl->active_tree()->root_layer()->children()[0]->SetPosition(
       gfx::PointF());
-  EXPECT_TRUE(layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
   layer_tree_host_impl->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   layer_tree_host_impl->SwapBuffers(frame);
 
   // Make sure that partial swap is constrained to the viewport dimensions
   // expected damage rect: gfx::Rect(500, 500);
   // expected swap rect: flipped damage rect, but also clamped to viewport
   EXPECT_EQ(TestContextSupport::PARTIAL_SWAP,
             context_provider->support()->last_swap_type());
   gfx::Rect expected_swap_rect(0, 500-28, 26, 28);
   EXPECT_EQ(expected_swap_rect.ToString(),
             context_provider->support()->
                 last_partial_swap_rect().ToString());
 
   layer_tree_host_impl->SetViewportSize(gfx::Size(10, 10));
   // This will damage everything.
   layer_tree_host_impl->active_tree()->root_layer()->SetBackgroundColor(
       SK_ColorBLACK);
-  EXPECT_TRUE(layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            layer_tree_host_impl->PrepareToDraw(&frame, gfx::Rect()));
   layer_tree_host_impl->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   layer_tree_host_impl->SwapBuffers(frame);
 
   EXPECT_EQ(TestContextSupport::SWAP,
             context_provider->support()->last_swap_type());
 }
 
 TEST_F(LayerTreeHostImplTest, RootLayerDoesntCreateExtraSurface) {
   scoped_ptr<LayerImpl> root =
       FakeDrawableLayerImpl::Create(host_impl_->active_tree(), 1);
   scoped_ptr<LayerImpl> child =
       FakeDrawableLayerImpl::Create(host_impl_->active_tree(), 2);
   child->SetAnchorPoint(gfx::PointF());
   child->SetBounds(gfx::Size(10, 10));
   child->SetContentBounds(gfx::Size(10, 10));
   child->SetDrawsContent(true);
   root->SetAnchorPoint(gfx::PointF());
   root->SetBounds(gfx::Size(10, 10));
   root->SetContentBounds(gfx::Size(10, 10));
   root->SetDrawsContent(true);
   root->SetForceRenderSurface(true);
   root->AddChild(child.Pass());
 
   host_impl_->active_tree()->SetRootLayer(root.Pass());
 
   LayerTreeHostImpl::FrameData frame;
 
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   EXPECT_EQ(1u, frame.render_surface_layer_list->size());
   EXPECT_EQ(1u, frame.render_passes.size());
   host_impl_->DidDrawAllLayers(frame);
 }
 
 class FakeLayerWithQuads : public LayerImpl {
  public:
   static scoped_ptr<LayerImpl> Create(LayerTreeImpl* tree_impl, int id) {
     return scoped_ptr<LayerImpl>(new FakeLayerWithQuads(tree_impl, id));
   }
@@ skipping 114 matching lines @@
   LayerTreeSettings settings = DefaultSettings();
   settings.partial_swap_enabled = false;
   CreateHostImpl(settings, output_surface.Pass());
   SetupRootLayerImpl(FakeLayerWithQuads::Create(host_impl_->active_tree(), 1));
 
   // Without partial swap, and no clipping, no scissor is set.
   harness.MustDrawSolidQuad();
   harness.MustSetNoScissor();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
   Mock::VerifyAndClearExpectations(&mock_context);
 
   // Without partial swap, but a layer does clip its subtree, one scissor is
   // set.
   host_impl_->active_tree()->root_layer()->SetMasksToBounds(true);
   harness.MustDrawSolidQuad();
   harness.MustSetScissor(0, 0, 10, 10);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
   Mock::VerifyAndClearExpectations(&mock_context);
 }
 
 TEST_F(LayerTreeHostImplTest, PartialSwap) {
   scoped_ptr<MockContext> context_owned(new MockContext);
   MockContext* mock_context = context_owned.get();
   scoped_ptr<OutputSurface> output_surface(FakeOutputSurface::Create3d(
       context_owned.PassAs<TestWebGraphicsContext3D>()));
   MockContextHarness harness(mock_context);
 
   LayerTreeSettings settings = DefaultSettings();
   settings.partial_swap_enabled = true;
   CreateHostImpl(settings, output_surface.Pass());
   SetupRootLayerImpl(FakeLayerWithQuads::Create(host_impl_->active_tree(), 1));
 
   // The first frame is not a partially-swapped one.
   harness.MustSetScissor(0, 0, 10, 10);
   harness.MustDrawSolidQuad();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
   Mock::VerifyAndClearExpectations(&mock_context);
 
   // Damage a portion of the frame.
   host_impl_->active_tree()->root_layer()->SetUpdateRect(
       gfx::Rect(0, 0, 2, 3));
 
   // The second frame will be partially-swapped (the y coordinates are flipped).
   harness.MustSetScissor(0, 7, 2, 3);
   harness.MustDrawSolidQuad();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
   Mock::VerifyAndClearExpectations(&mock_context);
 }
 
 static scoped_ptr<LayerTreeHostImpl> SetupLayersForOpacity(
     bool partial_swap,
     LayerTreeHostImplClient* client,
     Proxy* proxy,
@@ skipping 70 matching lines @@
 
   my_host_impl->active_tree()->SetRootLayer(root.Pass());
   return my_host_impl.Pass();
 }
 
 TEST_F(LayerTreeHostImplTest, ContributingLayerEmptyScissorPartialSwap) {
   scoped_ptr<LayerTreeHostImpl> my_host_impl =
       SetupLayersForOpacity(true, this, &proxy_, &stats_instrumentation_);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(my_host_impl->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              my_host_impl->PrepareToDraw(&frame, gfx::Rect()));
 
     // Verify all quads have been computed
     ASSERT_EQ(2U, frame.render_passes.size());
     ASSERT_EQ(1U, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(1U, frame.render_passes[1]->quad_list.size());
     EXPECT_EQ(DrawQuad::SOLID_COLOR,
               frame.render_passes[0]->quad_list[0]->material);
     EXPECT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[1]->quad_list[0]->material);
 
     my_host_impl->DrawLayers(&frame, gfx::FrameTime::Now());
     my_host_impl->DidDrawAllLayers(frame);
   }
 }
 
 TEST_F(LayerTreeHostImplTest, ContributingLayerEmptyScissorNoPartialSwap) {
   scoped_ptr<LayerTreeHostImpl> my_host_impl =
       SetupLayersForOpacity(false, this, &proxy_, &stats_instrumentation_);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(my_host_impl->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              my_host_impl->PrepareToDraw(&frame, gfx::Rect()));
 
     // Verify all quads have been computed
     ASSERT_EQ(2U, frame.render_passes.size());
     ASSERT_EQ(1U, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(1U, frame.render_passes[1]->quad_list.size());
     EXPECT_EQ(DrawQuad::SOLID_COLOR,
               frame.render_passes[0]->quad_list[0]->material);
     EXPECT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[1]->quad_list[0]->material);
 
@@ skipping 35 matching lines @@
   io_surface_layer->SetContentBounds(gfx::Size(10, 10));
   io_surface_layer->SetDrawsContent(true);
   io_surface_layer->SetIOSurfaceProperties(1, gfx::Size(10, 10));
   root_layer->AddChild(io_surface_layer.PassAs<LayerImpl>());
 
   host_impl_->active_tree()->SetRootLayer(root_layer.Pass());
 
   EXPECT_EQ(0u, context3d->NumTextures());
 
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   host_impl_->SwapBuffers(frame);
 
   EXPECT_GT(context3d->NumTextures(), 0u);
 
   // Kill the layer tree.
   host_impl_->active_tree()->SetRootLayer(
       LayerImpl::Create(host_impl_->active_tree(), 100));
   // There should be no textures left in use after.
@@ skipping 24 matching lines @@
   SetupRootLayerImpl(LayerImpl::Create(host_impl_->active_tree(), 1));
   host_impl_->active_tree()->set_background_color(SK_ColorWHITE);
 
   // Verify one quad is drawn when transparent background set is not set.
   host_impl_->active_tree()->set_has_transparent_background(false);
   EXPECT_CALL(*mock_context, useProgram(_))
       .Times(1);
   EXPECT_CALL(*mock_context, drawElements(_, _, _, _))
       .Times(1);
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   Mock::VerifyAndClearExpectations(&mock_context);
 
   // Verify no quads are drawn when transparent background is set.
   host_impl_->active_tree()->set_has_transparent_background(true);
   host_impl_->SetFullRootLayerDamage();
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   Mock::VerifyAndClearExpectations(&mock_context);
 }
 
 TEST_F(LayerTreeHostImplTest, ReleaseContentsTextureShouldTriggerCommit) {
   set_reduce_memory_result(false);
 
   // If changing the memory limit wouldn't result in changing what was
   // committed, then no commit should be requested.
@@ skipping 36 matching lines @@
     : public LayerTreeHostImplTest {
  protected:
   virtual scoped_ptr<OutputSurface> CreateOutputSurface() OVERRIDE {
     return FakeOutputSurface::CreateDelegating3d().PassAs<OutputSurface>();
   }
 
   void DrawFrameAndTestDamage(const gfx::RectF& expected_damage) {
     bool expect_to_draw = !expected_damage.IsEmpty();
 
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     if (!expect_to_draw) {
       // With no damage, we don't draw, and no quads are created.
       ASSERT_EQ(0u, frame.render_passes.size());
     } else {
       ASSERT_EQ(1u, frame.render_passes.size());
 
       // Verify the damage rect for the root render pass.
       const RenderPass* root_render_pass = frame.render_passes.back();
       EXPECT_RECT_EQ(expected_damage, root_render_pass->damage_rect);
@@ skipping 130 matching lines @@
   mask_layer->SetDrawsContent(true);
 
 
   // Check that the tree scaling is correctly taken into account for the mask,
   // that should fully map onto the quad.
   float device_scale_factor = 1.f;
   host_impl_->SetViewportSize(root_size);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               render_pass_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
 
   // Applying a DSF should change the render surface size, but won't affect
   // which part of the mask is used.
   device_scale_factor = 2.f;
   gfx::Size device_viewport =
       gfx::ToFlooredSize(gfx::ScaleSize(root_size, device_scale_factor));
   host_impl_->SetViewportSize(device_viewport);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 200, 200).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               render_pass_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
 
   // Applying an equivalent content scale on the content layer and the mask
   // should still result in the same part of the mask being used.
   gfx::Size content_bounds =
       gfx::ToRoundedSize(gfx::ScaleSize(scaling_layer_size,
                                         device_scale_factor));
   content_layer->SetContentBounds(content_bounds);
   content_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   mask_layer->SetContentBounds(content_bounds);
   mask_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 200, 200).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
@@ skipping 42 matching lines @@
   mask_layer->SetPosition(gfx::PointF());
   mask_layer->SetAnchorPoint(gfx::PointF());
   mask_layer->SetDrawsContent(true);
 
   // Check that the mask fills the surface.
   float device_scale_factor = 1.f;
   host_impl_->SetViewportSize(root_size);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 50, 50).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               render_pass_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Applying a DSF should change the render surface size, but won't affect
   // which part of the mask is used.
   device_scale_factor = 2.f;
   gfx::Size device_viewport =
       gfx::ToFlooredSize(gfx::ScaleSize(root_size, device_scale_factor));
   host_impl_->SetViewportSize(device_viewport);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               render_pass_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Applying an equivalent content scale on the content layer and the mask
   // should still result in the same part of the mask being used.
   gfx::Size layer_size_large =
       gfx::ToRoundedSize(gfx::ScaleSize(layer_size, device_scale_factor));
   content_layer->SetContentBounds(layer_size_large);
   content_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   gfx::Size mask_size_large =
       gfx::ToRoundedSize(gfx::ScaleSize(mask_size, device_scale_factor));
   mask_layer->SetContentBounds(mask_size_large);
   mask_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               render_pass_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Applying a different contents scale to the mask layer means it will have
   // a larger texture, but it should use the same tex coords to cover the
   // layer it masks.
   mask_layer->SetContentBounds(mask_size);
   mask_layer->SetContentsScale(1.f, 1.f);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               render_pass_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
@@ skipping 47 matching lines @@
   mask_layer->SetPosition(gfx::PointF());
   mask_layer->SetAnchorPoint(gfx::PointF());
   mask_layer->SetDrawsContent(true);
 
   // Check that the mask fills the surface.
   float device_scale_factor = 1.f;
   host_impl_->SetViewportSize(root_size);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[1]->material);
     const RenderPassDrawQuad* replica_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[1]);
     EXPECT_TRUE(replica_quad->is_replica);
     EXPECT_EQ(gfx::Rect(0, 0, 50, 50).ToString(),
               replica_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               replica_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Applying a DSF should change the render surface size, but won't affect
   // which part of the mask is used.
   device_scale_factor = 2.f;
   gfx::Size device_viewport =
       gfx::ToFlooredSize(gfx::ScaleSize(root_size, device_scale_factor));
   host_impl_->SetViewportSize(device_viewport);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[1]->material);
     const RenderPassDrawQuad* replica_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[1]);
     EXPECT_TRUE(replica_quad->is_replica);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               replica_quad->rect.ToString());
@@ skipping 10 matching lines @@
       gfx::ToRoundedSize(gfx::ScaleSize(layer_size, device_scale_factor));
   content_layer->SetContentBounds(layer_size_large);
   content_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   gfx::Size mask_size_large =
       gfx::ToRoundedSize(gfx::ScaleSize(mask_size, device_scale_factor));
   mask_layer->SetContentBounds(mask_size_large);
   mask_layer->SetContentsScale(device_scale_factor, device_scale_factor);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[1]->material);
     const RenderPassDrawQuad* replica_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[1]);
     EXPECT_TRUE(replica_quad->is_replica);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               replica_quad->rect.ToString());
     EXPECT_EQ(gfx::RectF(0.f, 0.f, 1.f, 1.f).ToString(),
               replica_quad->mask_uv_rect.ToString());
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Applying a different contents scale to the mask layer means it will have
   // a larger texture, but it should use the same tex coords to cover the
   // layer it masks.
   mask_layer->SetContentBounds(mask_size);
   mask_layer->SetContentsScale(1.f, 1.f);
   host_impl_->active_tree()->set_needs_update_draw_properties();
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[1]->material);
     const RenderPassDrawQuad* replica_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[1]);
     EXPECT_TRUE(replica_quad->is_replica);
     EXPECT_EQ(gfx::Rect(0, 0, 100, 100).ToString(),
               replica_quad->rect.ToString());
@@ skipping 59 matching lines @@
   mask_layer->SetContentBounds(mask_size);
   mask_layer->SetPosition(gfx::PointF());
   mask_layer->SetAnchorPoint(gfx::PointF());
   mask_layer->SetDrawsContent(true);
 
   float device_scale_factor = 1.f;
   host_impl_->SetViewportSize(root_size);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
 
     // The surface is 100x50.
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_FALSE(render_pass_quad->is_replica);
@@ skipping 13 matching lines @@
 
     host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
     host_impl_->DidDrawAllLayers(frame);
   }
 
   // Move the child to (-50, 0) instead. Now the mask should be moved to still
   // cover the layer being replicated.
   content_child_layer->SetPosition(gfx::Point(-50, 0));
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(2u, frame.render_passes[0]->quad_list.size());
 
     // The surface is 100x50 with its origin at (-50, 0).
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_FALSE(render_pass_quad->is_replica);
@@ skipping 78 matching lines @@
   mask_layer->SetContentBounds(mask_size);
   mask_layer->SetPosition(gfx::PointF());
   mask_layer->SetAnchorPoint(gfx::PointF());
   mask_layer->SetDrawsContent(true);
 
   float device_scale_factor = 1.f;
   host_impl_->SetViewportSize(root_size);
   host_impl_->SetDeviceScaleFactor(device_scale_factor);
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
     ASSERT_EQ(1u, frame.render_passes.size());
     ASSERT_EQ(1u, frame.render_passes[0]->quad_list.size());
 
     // The surface is clipped to 10x20.
     ASSERT_EQ(DrawQuad::RENDER_PASS,
               frame.render_passes[0]->quad_list[0]->material);
     const RenderPassDrawQuad* render_pass_quad =
         RenderPassDrawQuad::MaterialCast(frame.render_passes[0]->quad_list[0]);
     EXPECT_FALSE(render_pass_quad->is_replica);
@@ skipping 61 matching lines @@
   scrolling_layer->SetScrollable(true);
   scrolling_layer->SetMaxScrollOffset(scroll_offset);
   scrolling_layer->SetScrollOffset(scroll_offset);
 
   host_impl_->ActivatePendingTree();
 
   host_impl_->active_tree()->UpdateDrawProperties();
   ASSERT_EQ(1u, host_impl_->active_tree()->RenderSurfaceLayerList().size());
 
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
 
   ASSERT_EQ(1u, frame.render_passes.size());
   ASSERT_LE(1u, frame.render_passes[0]->quad_list.size());
   const DrawQuad* quad = frame.render_passes[0]->quad_list[0];
 
   float edge[24];
   gfx::QuadF device_layer_quad;
   bool antialiased =
       GLRendererWithSetupQuadForAntialiasing::SetupQuadForAntialiasing(
           quad->quadTransform(), quad, &device_layer_quad, edge);
@@ skipping 13 matching lines @@
     swap_buffers_complete_++;
   }
 
   int swap_buffers_complete_;
 };
 
 TEST_F(CompositorFrameMetadataTest, CompositorFrameAckCountsAsSwapComplete) {
   SetupRootLayerImpl(FakeLayerWithQuads::Create(host_impl_->active_tree(), 1));
   {
     LayerTreeHostImpl::FrameData frame;
-    EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+    EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+              host_impl_->PrepareToDraw(&frame, gfx::Rect()));
     host_impl_->DrawLayers(&frame, base::TimeTicks());
     host_impl_->DidDrawAllLayers(frame);
   }
   CompositorFrameAck ack;
   host_impl_->ReclaimResources(&ack);
   host_impl_->OnSwapBuffersComplete();
   EXPECT_EQ(swap_buffers_complete_, 1);
 }
 
 class CountingSoftwareDevice : public SoftwareOutputDevice {
@@ skipping 59 matching lines @@
   FakeVideoFrameProvider provider;
   scoped_ptr<VideoLayerImpl> video_layer =
       VideoLayerImpl::Create(host_impl_->active_tree(), 2, &provider);
   video_layer->SetBounds(gfx::Size(10, 10));
   video_layer->SetContentBounds(gfx::Size(10, 10));
   video_layer->SetDrawsContent(true);
   root_layer->AddChild(video_layer.PassAs<LayerImpl>());
   SetupRootLayerImpl(root_layer.PassAs<LayerImpl>());
 
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   EXPECT_EQ(1u, frame.will_draw_layers.size());
   EXPECT_EQ(host_impl_->active_tree()->root_layer(), frame.will_draw_layers[0]);
 }
 
 class LayerTreeHostImplTestDeferredInitialize : public LayerTreeHostImplTest {
  protected:
   virtual void SetUp() OVERRIDE {
@@ skipping 284 matching lines @@
 
   SetupRootLayerImpl(LayerImpl::Create(host_impl_->active_tree(), 1));
 
   ScopedPtrVector<CopyOutputRequest> requests;
   requests.push_back(CopyOutputRequest::CreateRequest(
       base::Bind(&ShutdownReleasesContext_Callback)));
 
   host_impl_->active_tree()->root_layer()->PassCopyRequests(&requests);
 
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
 
   // The CopyOutputResult's callback has a ref on the ContextProvider and a
   // texture in a texture mailbox.
   EXPECT_FALSE(context_provider->HasOneRef());
   EXPECT_EQ(1u, context_provider->TestContext3d()->NumTextures());
 
   host_impl_.reset();
 
@@ skipping 167 matching lines @@
   ui::LatencyInfo latency_info;
   latency_info.AddLatencyNumber(
       ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT, 0, 0);
   scoped_ptr<SwapPromise> swap_promise(
       new LatencyInfoSwapPromise(latency_info));
   host_impl_->active_tree()->QueueSwapPromise(swap_promise.Pass());
   host_impl_->SetNeedsRedraw();
 
   gfx::Rect full_frame_damage(host_impl_->DrawViewportSize());
   LayerTreeHostImpl::FrameData frame;
-  EXPECT_TRUE(host_impl_->PrepareToDraw(&frame, gfx::Rect()));
+  EXPECT_EQ(DrawSwapReadbackResult::DID_DRAW,
+            host_impl_->PrepareToDraw(&frame, gfx::Rect()));
   host_impl_->DrawLayers(&frame, gfx::FrameTime::Now());
   host_impl_->DidDrawAllLayers(frame);
   EXPECT_TRUE(host_impl_->SwapBuffers(frame));
 
   const std::vector<ui::LatencyInfo>& metadata_latency_after =
       fake_output_surface->last_sent_frame().metadata.latency_info;
   EXPECT_EQ(1u, metadata_latency_after.size());
   EXPECT_TRUE(metadata_latency_after[0].FindLatency(
       ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT, 0, NULL));
 }
@@ skipping 63 matching lines @@
                                      &set_needs_redraw_count));
     // Empty damage rect won't signal the monitor.
     host_impl_->SetNeedsRedrawRect(gfx::Rect());
     EXPECT_EQ(0, set_needs_commit_count);
     EXPECT_EQ(2, set_needs_redraw_count);
   }
 }
 
 }  // namespace
 }  // namespace cc