cc: Enable composited border-radius scrolling.

cc/layers/solid_color_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/solid_color_layer_impl.h"
 
 #include <algorithm>
 
 #include "cc/layers/append_quads_data.h"
 #include "cc/quads/solid_color_draw_quad.h"
@@ skipping 15 matching lines @@
     LayerTreeImpl* tree_impl) {
   return SolidColorLayerImpl::Create(tree_impl, id());
 }
 
 void SolidColorLayerImpl::AppendSolidQuads(
     RenderPass* render_pass,
     const Occlusion& occlusion_in_layer_space,
     SharedQuadState* shared_quad_state,
     const gfx::Rect& visible_layer_rect,
     SkColor color,
-    AppendQuadsData* append_quads_data) {
+    AppendQuadsData* append_quads_data,
+    Layer::LayerMaskType mask_type) {
   float alpha =
       (SkColorGetA(color) * (1.0f / 255.0f)) * shared_quad_state->opacity;
   DCHECK_EQ(SkBlendMode::kSrcOver, shared_quad_state->blend_mode);
-  if (alpha < std::numeric_limits<float>::epsilon())
+  if (alpha < std::numeric_limits<float>::epsilon() &&
+      mask_type != Layer::LayerMaskType::MULTI_TEXTURE_MASK)

[enne (OOO), 2017/05/12 17:51:33]

Why must these noop solid color quads not be skipped for multi texture masks?

[sunxd, 2017/05/15 17:57:36]

It was because mask layer's opacity is not calculated. I reverted the change
here and add the computation code.

     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,
@@ skipping 23 matching lines @@
       render_pass->CreateAndAppendSharedQuadState();
   PopulateSharedQuadState(shared_quad_state);
 
   AppendDebugBorderQuad(render_pass, bounds(), shared_quad_state,
                         append_quads_data);
 
   // TODO(hendrikw): We need to pass the visible content rect rather than
   // |bounds()| here.
   AppendSolidQuads(render_pass, draw_properties().occlusion_in_content_space,
                    shared_quad_state, gfx::Rect(bounds()), background_color(),
-                   append_quads_data);
+                   append_quads_data, Layer::LayerMaskType::NOT_MASK);
 }
 
 const char* SolidColorLayerImpl::LayerTypeAsString() const {
   return "cc::SolidColorLayerImpl";
 }
 
 }  // namespace cc