Adding support for blending in cc::SoftwareRenderer

cc/output/software_renderer.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/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 236 matching lines @@
     // layer, disable AA if any interior edges are present. crbug.com/248175
     bool all_four_edges_are_exterior = quad->IsTopEdge() &&
                                        quad->IsLeftEdge() &&
                                        quad->IsBottomEdge() &&
                                        quad->IsRightEdge();
     if (settings_->allow_antialiasing && all_four_edges_are_exterior)
       current_paint_.setAntiAlias(true);
     current_paint_.setFilterLevel(SkPaint::kLow_FilterLevel);
   }
 
-  if (quad->ShouldDrawWithBlending()) {
+  if (quad->ShouldDrawWithBlending() ||
+      quad->shared_quad_state->blend_mode != SkXfermode::kSrcOver_Mode) {
     current_paint_.setAlpha(quad->opacity() * 255);
-    current_paint_.setXfermodeMode(SkXfermode::kSrcOver_Mode);
+    current_paint_.setXfermodeMode(quad->shared_quad_state->blend_mode);
   } else {
     current_paint_.setXfermodeMode(SkXfermode::kSrc_Mode);
   }
 
   switch (quad->material) {
     case DrawQuad::CHECKERBOARD:
       DrawCheckerboardQuad(frame, CheckerboardDrawQuad::MaterialCast(quad));
       break;
     case DrawQuad::DEBUG_BORDER:
       DrawDebugBorderQuad(frame, DebugBorderDrawQuad::MaterialCast(quad));
@@ skipping 268 matching lines @@
 
     SkLayerRasterizer::Builder builder;
     builder.addLayer(mask_paint);
 
     skia::RefPtr<SkLayerRasterizer> mask_rasterizer =
         skia::AdoptRef(builder.detachRasterizer());
 
     current_paint_.setRasterizer(mask_rasterizer.get());
     current_canvas_->drawRect(dest_visible_rect, current_paint_);
   } else {
-    // TODO(skaslev): Apply background filters and blend with content
+    // TODO(skaslev): Apply background filters
     current_canvas_->drawRect(dest_visible_rect, current_paint_);
   }
 }
 
 void SoftwareRenderer::DrawUnsupportedQuad(const DrawingFrame* frame,
                                            const DrawQuad* quad) {
 #ifdef NDEBUG
   current_paint_.setColor(SK_ColorWHITE);
 #else
   current_paint_.setColor(SK_ColorMAGENTA);
@@ skipping 41 matching lines @@
 }
 
 void SoftwareRenderer::DidChangeVisibility() {
   if (visible())
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 }  // namespace cc