cc: Reduce the SolidColorDrawQuad generated by chrome

Since PictureLayerImpl::AppendQuads and SolidColorLayerImpl
::AppendSolidQuads both use scale=1 for its shared quad state,
pages like chrome://about can generate ~200 SCDQ on hi dpi
phones (e.g. pixel 2).

SolidColorDrawQuads are cheap to draw. In this CL, I re-visited
the tile management and generate only 1 SolidColorDrawQuad.

I tested the performance on cc_scroll_200_layer_grid, and
thread_GPU_cpu_time_per_frame is improved to 2.215 from 2.754.

Performance result summary:
https://x20.corp.google.com/users/yi/yiyix/www/1%20solid%20color%20draw%20quad%20analysis

Bug: 879379

TBR=kbr@chromium.org

Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I8deaf29d1f0ed8f2d052ff77c8673b4e39877ab6
Reviewed-on: https://chromium-review.googlesource.com/c/1258386
Commit-Queue: Yi Xu <yiyix@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598867}

cc/layers/picture_layer_impl_unittest.cc

@@ -3369,7 +3369,7 @@ TEST_F(PictureLayerImplTest, OcclusionOnSolidColorPictureLayer) {
 
   {
     SCOPED_TRACE("Scaled occlusion");
-    gfx::Rect occluded(300, 0, 400, 2000);
+    gfx::Rect occluded(300, 0, 2000, 2000);
     impl.AppendQuadsWithOcclusion(active_layer(), occluded);
 
     size_t partial_occluded_count = 0;
@@ -3377,11 +3377,9 @@ TEST_F(PictureLayerImplTest, OcclusionOnSolidColorPictureLayer) {
                                             &partial_occluded_count);
     // Because of the implementation of test helper AppendQuadsWithOcclusion,
     // the occlusion will have a scale transform resulted from the device scale
-    // factor. However, the AppendQuads function will try to tile a solid color
-    // layer ignoring the scale factor, and its visible layer bounds is 500x500.
-    // So we end up having 4 partially occluded quads.
-    EXPECT_EQ(4u, impl.quad_list().size());
-    EXPECT_EQ(4u, partial_occluded_count);
+    // factor. A single partially overlapped DrawQuad of 500x500 will be added.
+    EXPECT_EQ(1u, impl.quad_list().size());
+    EXPECT_EQ(1u, partial_occluded_count);
   }
 }
 
@@ -3409,7 +3407,7 @@ TEST_F(PictureLayerImplTest, IgnoreOcclusionOnSolidColorMask) {
                                             &partial_occluded_count);
     // None of the quads shall be occluded because mask layers ignores
     // occlusion.
-    EXPECT_EQ(16u, impl.quad_list().size());
+    EXPECT_EQ(1u, impl.quad_list().size());
     EXPECT_EQ(0u, partial_occluded_count);
   }
 }

cc/layers/solid_color_layer_impl.cc

@@ -13,10 +13,6 @@
 
 namespace cc {
 
-namespace {
-const int kSolidQuadTileSize = 256;
-}
-
 SolidColorLayerImpl::SolidColorLayerImpl(LayerTreeImpl* tree_impl, int id)
     : LayerImpl(tree_impl, id) {
 }
@@ -41,32 +37,12 @@ void SolidColorLayerImpl::AppendSolidQuads(
   DCHECK_EQ(SkBlendMode::kSrcOver, shared_quad_state->blend_mode);
   if (alpha < std::numeric_limits<float>::epsilon())
     return;
-  // We create a series of smaller quads instead of just one large one so that
-  // the culler can reduce the total pixels drawn.
-  int right = visible_layer_rect.right();
-  int bottom = visible_layer_rect.bottom();
-  for (int x = visible_layer_rect.x(); x < visible_layer_rect.right();
-       x += kSolidQuadTileSize) {
-    for (int y = visible_layer_rect.y(); y < visible_layer_rect.bottom();
-         y += kSolidQuadTileSize) {
-      gfx::Rect quad_rect(x,
-                          y,
-                          std::min(right - x, kSolidQuadTileSize),
-                          std::min(bottom - y, kSolidQuadTileSize));
-      gfx::Rect visible_quad_rect =
-          occlusion_in_layer_space.GetUnoccludedContentRect(quad_rect);
-      if (visible_quad_rect.IsEmpty())
-        continue;
-
-      append_quads_data->visible_layer_area +=
-          visible_quad_rect.width() * visible_quad_rect.height();
 
-      auto* quad =
-          render_pass->CreateAndAppendDrawQuad<viz::SolidColorDrawQuad>();
-      quad->SetNew(shared_quad_state, quad_rect, visible_quad_rect, color,
-                   force_anti_aliasing_off);
-    }
-  }
+  gfx::Rect visible_quad_rect =
+      occlusion_in_layer_space.GetUnoccludedContentRect(visible_layer_rect);
+  auto* quad = render_pass->CreateAndAppendDrawQuad<viz::SolidColorDrawQuad>();
+  quad->SetNew(shared_quad_state, visible_layer_rect, visible_quad_rect, color,
+               force_anti_aliasing_off);
 }
 
 void SolidColorLayerImpl::AppendQuads(viz::RenderPass* render_pass,

cc/layers/solid_color_layer_impl_unittest.cc

@@ -263,7 +263,7 @@ TEST(SolidColorLayerImplTest, Occlusion) {
 
     LayerTestCommon::VerifyQuadsExactlyCoverRect(impl.quad_list(),
                                                  gfx::Rect(layer_size));
-    EXPECT_EQ(16u, impl.quad_list().size());
+    EXPECT_EQ(1u, impl.quad_list().size());
   }
 
   {
@@ -277,15 +277,15 @@ TEST(SolidColorLayerImplTest, Occlusion) {
 
   {
     SCOPED_TRACE("Partial occlusion");
-    gfx::Rect occluded(200, 200, 256 * 3, 256 * 3);
+    gfx::Rect occluded(200, 0, 800, 1000);
     impl.AppendQuadsWithOcclusion(solid_color_layer_impl, occluded);
 
     size_t partially_occluded_count = 0;
     LayerTestCommon::VerifyQuadsAreOccluded(
         impl.quad_list(), occluded, &partially_occluded_count);
     // 4 quads are completely occluded, 8 are partially occluded.
-    EXPECT_EQ(16u - 4u, impl.quad_list().size());
-    EXPECT_EQ(8u, partially_occluded_count);
+    EXPECT_EQ(1u, impl.quad_list().size());
+    EXPECT_EQ(1u, partially_occluded_count);
   }
 }
 

content/test/gpu/gpu_tests/pixel_expectations.py

@@ -138,3 +138,6 @@ class PixelExpectations(GpuTestExpectations):
         ['android', ('qualcomm', 'Adreno (TM) 420')], bug=883500)
     self.Fail('Pixel_BackgroundImage',
         ['android', ('qualcomm', 'Adreno (TM) 430')], bug=883500)
+
+    # TODO(yiyix): remove expectation after rebaseline.
+    self.Fail("Pixel_CSS3DBlueBox", bug=879379)

content/test/gpu/gpu_tests/pixel_test_pages.py

@@ -114,7 +114,7 @@ def DefaultPages(base_name):
       'pixel_css3d.html',
       base_name + '_CSS3DBlueBox',
       test_rect=[0, 0, 300, 300],
-      revision=22),
+      revision=23),
 
     PixelTestPage(
       'pixel_webgl_aa_alpha.html',