cc: Enable non-opaque harware overlays.

cc/output/overlay_candidate.cc

 // Copyright 2014 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/overlay_candidate.h"
 
 #include <algorithm>
 #include <limits>
 #include "base/logging.h"
 #include "cc/base/math_util.h"
@@ skipping 177 matching lines @@
 }
 
 OverlayCandidate::OverlayCandidate(const OverlayCandidate& other) = default;
 
 OverlayCandidate::~OverlayCandidate() {}
 
 // static
 bool OverlayCandidate::FromDrawQuad(ResourceProvider* resource_provider,
                                     const DrawQuad* quad,
                                     OverlayCandidate* candidate) {
-  if (quad->ShouldDrawWithBlending() ||
-      quad->shared_quad_state->opacity != 1.f ||
-      quad->shared_quad_state->blend_mode != SkBlendMode::kSrcOver)
+  // We don't support an opacity value different than one for an overlay plane.
+  if (quad->shared_quad_state->opacity != 1.f)
+    return false;
+  // We support only kSrc (no blending) and kSrcOver (blending with premul).
+  if (!(quad->shared_quad_state->blend_mode == SkBlendMode::kSrc ||
+        quad->shared_quad_state->blend_mode == SkBlendMode::kSrcOver))
     return false;
 
   auto& transform = quad->shared_quad_state->quad_to_target_transform;
   candidate->display_rect = gfx::RectF(quad->rect);
   transform.TransformRect(&candidate->display_rect);
   candidate->quad_rect_in_target_space =
       MathUtil::MapEnclosingClippedRect(transform, quad->rect);
 
   candidate->clip_rect = quad->shared_quad_state->clip_rect;
   candidate->is_clipped = quad->shared_quad_state->is_clipped;
@@ skipping 131 matching lines @@
 
 OverlayCandidateList& OverlayCandidateList::operator=(
     OverlayCandidateList&& other) = default;
 
 void OverlayCandidateList::AddPromotionHint(const OverlayCandidate& candidate) {
   promotion_hint_info_map_[candidate.resource_id] =
       candidate.display_rect.origin();
 }
 
 }  // namespace cc