Allow task pools to reason about transparency.

cc/raster/bitmap_tile_task_worker_pool.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/raster/bitmap_tile_task_worker_pool.h"
 
 #include <algorithm>
 
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 161 matching lines @@
        it != completed_tasks_.end(); ++it) {
     TileTask* task = static_cast<TileTask*>(it->get());
 
     task->WillComplete();
     task->CompleteOnOriginThread(this);
     task->DidComplete();
   }
   completed_tasks_.clear();
 }
 
-ResourceFormat BitmapTileTaskWorkerPool::GetResourceFormat() const {
+ResourceFormat BitmapTileTaskWorkerPool::GetResourceFormat(
+    bool must_support_alpha) const {
   return resource_provider_->best_texture_format();
 }
 
-bool BitmapTileTaskWorkerPool::GetResourceRequiresSwizzle() const {
-  return !PlatformColor::SameComponentOrder(GetResourceFormat());
+bool BitmapTileTaskWorkerPool::GetResourceRequiresSwizzle(
+    bool must_support_alpha) const {
+  return !PlatformColor::SameComponentOrder(
+      GetResourceFormat(must_support_alpha));
 }
 
 scoped_ptr<RasterBuffer> BitmapTileTaskWorkerPool::AcquireBufferForRaster(
     const Resource* resource,
     uint64_t resource_content_id,
     uint64_t previous_content_id) {
   return scoped_ptr<RasterBuffer>(new RasterBufferImpl(
       resource_provider_, resource, resource_content_id, previous_content_id));
 }
 
@@ skipping 23 matching lines @@
       new base::trace_event::TracedValue();
 
   state->BeginArray("tasks_pending");
   for (TaskSet task_set = 0; task_set < kNumberOfTaskSets; ++task_set)
     state->AppendBoolean(tasks_pending_[task_set]);
   state->EndArray();
   return state;
 }
 
 }  // namespace cc