Blend TextureLayer background-color at draw time.

cc/output/gl_renderer.cc

Index: cc/output/gl_renderer.cc
diff --git a/cc/output/gl_renderer.cc b/cc/output/gl_renderer.cc
index 1528703751654f7e2f5a07605c0e74b97320465c..96b4a9f59ffbd621a7f29c012f60b2c9a482e7d3 100644
--- a/cc/output/gl_renderer.cc
+++ b/cc/output/gl_renderer.cc
@@ -98,6 +98,19 @@ Float4 UVTransform(const TextureDrawQuad* quad) {
   return xform;
 }
 
+Float4 PremultipliedColor(SkColor color) {
+  const float factor = 1.0f / 255.0f;
+  const float alpha = SkColorGetA(color) * factor;
+
+  Float4 result = { {
+      SkColorGetR(color) * factor * alpha,
+      SkColorGetG(color) * factor * alpha,
+      SkColorGetB(color) * factor * alpha,
+      alpha
+  } };
+  return result;
+}
+
 // Smallest unit that impact anti-aliasing output. We use this to
 // determine when anti-aliasing is unnecessary.
 const float kAntiAliasingEpsilon = 1.0f / 1024.0f;
@@ -1651,12 +1664,13 @@ struct TextureProgramBinding {
     program_id = program->program();
     sampler_location = program->fragment_shader().sampler_location();
     matrix_location = program->vertex_shader().matrix_location();
-    alpha_location = program->fragment_shader().alpha_location();
+    background_color_location =
+        program->fragment_shader().background_color_location();
   }
   int program_id;
   int sampler_location;
   int matrix_location;
-  int alpha_location;
+  int background_color_location;
 };
 
 struct TexTransformTextureProgramBinding : TextureProgramBinding {
@@ -1710,6 +1724,12 @@ void GLRenderer::FlushTextureQuadCache() {
           static_cast<int>(draw_cache_.uv_xform_location),
           static_cast<int>(draw_cache_.uv_xform_data.size()),
           reinterpret_cast<float*>(&draw_cache_.uv_xform_data.front())));
+
+  Float4 background_color = PremultipliedColor(draw_cache_.background_color);
+  GLC(context_,
+      context_->uniform4fv(
+          draw_cache_.background_color_location, 1, background_color.data));
+
   GLC(context_,
       context_->uniform1fv(
           static_cast<int>(draw_cache_.vertex_opacity_location),
@@ -1750,13 +1770,16 @@ void GLRenderer::EnqueueTextureQuad(const DrawingFrame* frame,
   if (draw_cache_.program_id != binding.program_id ||
       draw_cache_.resource_id != resource_id ||
       draw_cache_.needs_blending != quad->ShouldDrawWithBlending() ||
+      draw_cache_.background_color != quad->background_color ||
       draw_cache_.matrix_data.size() >= 8) {
     FlushTextureQuadCache();
     draw_cache_.program_id = binding.program_id;
     draw_cache_.resource_id = resource_id;
     draw_cache_.needs_blending = quad->ShouldDrawWithBlending();
+    draw_cache_.background_color = quad->background_color;
 
     draw_cache_.uv_xform_location = binding.tex_transform_location;
+    draw_cache_.background_color_location = binding.background_color_location;
     draw_cache_.vertex_opacity_location = binding.vertex_opacity_location;
     draw_cache_.matrix_location = binding.matrix_location;
     draw_cache_.sampler_location = binding.sampler_location;
@@ -1805,6 +1828,11 @@ void GLRenderer::DrawTextureQuad(const DrawingFrame* frame,
                            uv_xform.data[2],
                            uv_xform.data[3]));
 
+  Float4 background_color = PremultipliedColor(quad->background_color);
+  GLC(Context(),
+      Context()->uniform4fv(
+          binding.background_color_location, 1, background_color.data));
+
   GLC(Context(),
       Context()->uniform1fv(
           binding.vertex_opacity_location, 4, quad->vertex_opacity));