Allow task pools to reason about transparency.

cc/resources/resource_provider.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/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/atomic_sequence_num.h"
@@ skipping 358 matching lines @@
        itr != resources_.end(); ++itr) {
     DCHECK_NE(RESOURCE_TYPE_GL_TEXTURE, itr->second.type);
   }
 #endif  // DCHECK_IS_ON()
 
   texture_id_allocator_ = nullptr;
   buffer_id_allocator_ = nullptr;
   gl->Finish();
 }
 
+ResourceFormat ResourceProvider::memory_efficient_texture_format(
+    bool must_support_alpha) const {
+  return use_rgba_4444_texture_format_ ? RGBA_4444 : best_texture_format_;
+}
+
 bool ResourceProvider::InUseByConsumer(ResourceId id) {
   Resource* resource = GetResource(id);
   return resource->lock_for_read_count > 0 || resource->exported_count > 0 ||
          resource->lost;
 }
 
 bool ResourceProvider::IsLost(ResourceId id) {
   Resource* resource = GetResource(id);
   return resource->lost;
 }
@@ skipping 1271 matching lines @@
       const int kImportance = 2;
       pmd->CreateSharedGlobalAllocatorDump(guid);
       pmd->AddOwnershipEdge(dump->guid(), guid, kImportance);
     }
   }
 
   return true;
 }
 
 }  // namespace cc