Only emit a fallback SurfaceDrawQuad if differs from primary

cc/layers/surface_layer_impl_unittest.cc

Index: cc/layers/surface_layer_impl_unittest.cc
diff --git a/cc/layers/surface_layer_impl_unittest.cc b/cc/layers/surface_layer_impl_unittest.cc
index ff83229e1a0adb331d4271a88833a5598c29eb95..1b41a538677141d1a48e4f3d53a1d184a682fb57 100644
--- a/cc/layers/surface_layer_impl_unittest.cc
+++ b/cc/layers/surface_layer_impl_unittest.cc
@@ -198,5 +198,105 @@ TEST(SurfaceLayerImplTest, SurfaceStretchedToLayerBounds) {
   EXPECT_EQ(transformed_quad_rect, transformed_layer_rect);
 }
 
+// This test verifies that two SurfaceDrawQuads are emitted if a
+// SurfaceLayerImpl holds both a primary and fallback SurfaceInfo.
+TEST(SurfaceLayerImplTest, SurfaceLayerImplEmitsTwoDrawQuadsIfUniqueFallback) {
+  LayerTestCommon::LayerImplTest impl;
+  SurfaceLayerImpl* surface_layer_impl =
+      impl.AddChildToRoot<SurfaceLayerImpl>();
+
+  // Populate the primary SurfaceInfo.
+  const LocalSurfaceId kArbitraryLocalSurfaceId1(
+      9, base::UnguessableToken::Create());
+  SurfaceId surface_id1(kArbitraryFrameSinkId, kArbitraryLocalSurfaceId1);
+  float surface_scale1 = 1.f;
+  gfx::Size surface_size1(300, 300);
+  SurfaceInfo primary_surface_info(surface_id1, surface_scale1, surface_size1);
+
+  // Populate the fallback SurfaceInfo.
+  const LocalSurfaceId kArbitraryLocalSurfaceId2(
+      7, base::UnguessableToken::Create());
+  SurfaceId surface_id2(kArbitraryFrameSinkId, kArbitraryLocalSurfaceId2);
+  float surface_scale2 = 2.f;
+  gfx::Size surface_size2(400, 400);
+  SurfaceInfo fallback_surface_info(surface_id2, surface_scale2, surface_size2);
+
+  gfx::Size layer_size(400, 100);
+
+  // Populate the SurfaceLayerImpl ensuring that the primary and fallback
+  // SurfaceInfos are different.
+  surface_layer_impl->SetBounds(layer_size);
+  surface_layer_impl->SetDrawsContent(true);
+  surface_layer_impl->SetPrimarySurfaceInfo(primary_surface_info);
+  surface_layer_impl->SetFallbackSurfaceInfo(fallback_surface_info);
+
+  gfx::Size viewport_size(1000, 1000);
+  impl.CalcDrawProps(viewport_size);
+
+  std::unique_ptr<RenderPass> render_pass = RenderPass::Create();
+  AppendQuadsData data;
+  surface_layer_impl->AppendQuads(render_pass.get(), &data);
+
+  ASSERT_EQ(2u, render_pass->quad_list.size());
+  const SurfaceDrawQuad* surface_draw_quad1 =
+      SurfaceDrawQuad::MaterialCast(render_pass->quad_list.ElementAt(0));
+  ASSERT_TRUE(surface_draw_quad1);
+  const SurfaceDrawQuad* surface_draw_quad2 =
+      SurfaceDrawQuad::MaterialCast(render_pass->quad_list.ElementAt(1));
+  ASSERT_TRUE(surface_draw_quad2);
+
+  EXPECT_EQ(SurfaceDrawQuadType::PRIMARY,
+            surface_draw_quad1->surface_draw_quad_type);
+  EXPECT_EQ(surface_id1, surface_draw_quad1->surface_id);
+  EXPECT_EQ(surface_draw_quad2, surface_draw_quad1->fallback_quad);
+  EXPECT_EQ(SurfaceDrawQuadType::FALLBACK,
+            surface_draw_quad2->surface_draw_quad_type);
+  EXPECT_EQ(surface_id2, surface_draw_quad2->surface_id);
+}
+
+// This test verifies that one SurfaceDrawQuad is emitted if a
+// SurfaceLayerImpl holds the same surface ID for both the primary
+// and fallback SurfaceInfo.
+TEST(SurfaceLayerImplTest,
+     SurfaceLayerImplEmitsOneDrawQuadsIfPrimaryMatchesFallback) {
+  LayerTestCommon::LayerImplTest impl;
+  SurfaceLayerImpl* surface_layer_impl =
+      impl.AddChildToRoot<SurfaceLayerImpl>();
+
+  // Populate the primary SurfaceInfo.
+  const LocalSurfaceId kArbitraryLocalSurfaceId1(
+      9, base::UnguessableToken::Create());
+  SurfaceId surface_id1(kArbitraryFrameSinkId, kArbitraryLocalSurfaceId1);
+  float surface_scale1 = 1.f;
+  gfx::Size surface_size1(300, 300);
+  SurfaceInfo primary_surface_info(surface_id1, surface_scale1, surface_size1);
+
+  gfx::Size layer_size(400, 100);
+
+  // Populate the SurfaceLayerImpl ensuring that the primary and fallback
+  // SurfaceInfos are the same.
+  surface_layer_impl->SetBounds(layer_size);
+  surface_layer_impl->SetDrawsContent(true);
+  surface_layer_impl->SetPrimarySurfaceInfo(primary_surface_info);
+  surface_layer_impl->SetFallbackSurfaceInfo(primary_surface_info);
+
+  gfx::Size viewport_size(1000, 1000);
+  impl.CalcDrawProps(viewport_size);
+
+  std::unique_ptr<RenderPass> render_pass = RenderPass::Create();
+  AppendQuadsData data;
+  surface_layer_impl->AppendQuads(render_pass.get(), &data);
+
+  ASSERT_EQ(1u, render_pass->quad_list.size());
+  const SurfaceDrawQuad* surface_draw_quad1 =
+      SurfaceDrawQuad::MaterialCast(render_pass->quad_list.ElementAt(0));
+  ASSERT_TRUE(surface_draw_quad1);
+
+  EXPECT_EQ(SurfaceDrawQuadType::PRIMARY,
+            surface_draw_quad1->surface_draw_quad_type);
+  EXPECT_EQ(surface_id1, surface_draw_quad1->surface_id);
+  EXPECT_FALSE(surface_draw_quad1->fallback_quad);
+}
+
 }  // namespace
 }  // namespace cc