cc: return resources via a ReturnedResource struct rather than TransferableResource

This allows us to return a count, as well as reducing the size significantly
since we don't need to return the mailbox.

This is built on top of https://codereview.chromium.org/23023005

BUG=263068

Review URL: https://chromiumcodereview.appspot.com/23097005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@218214 0039d316-1c4b-4281-b951-d872f2087c98

22 files changed, 213 insertions, 189 deletions

diff --git a/cc/cc.gyp b/cc/cc.gyp
index de2df18..cd9afeb 100644
--- a/cc/cc.gyp
+++ b/cc/cc.gyp
@@ -317,6 +317,7 @@
         'resources/resource_update_controller.h',
         'resources/resource_update_queue.cc',
         'resources/resource_update_queue.h',
+        'resources/returned_resource.h',
         'resources/scoped_resource.cc',
         'resources/scoped_resource.h',
         'resources/scoped_ui_resource.cc',
diff --git a/cc/layers/delegated_renderer_layer.cc b/cc/layers/delegated_renderer_layer.cc
index 45a432f..0ffa54a 100644
--- a/cc/layers/delegated_renderer_layer.cc
+++ b/cc/layers/delegated_renderer_layer.cc
@@ -70,10 +70,9 @@ void DelegatedRendererLayer::SetFrameData(
   if (frame_data_) {
     // Copy the resources from the last provided frame into the unused resources
     // list, as the new frame will provide its own resources.
-    unused_resources_for_child_compositor_.insert(
-        unused_resources_for_child_compositor_.end(),
-        frame_data_->resource_list.begin(),
-        frame_data_->resource_list.end());
+    TransferableResource::ReturnResources(
+        frame_data_->resource_list,
+        &unused_resources_for_child_compositor_);
   }
   frame_data_ = new_frame_data.Pass();
   if (!frame_data_->render_pass_list.empty()) {
@@ -87,7 +86,7 @@ void DelegatedRendererLayer::SetFrameData(
 }
 
 void DelegatedRendererLayer::TakeUnusedResourcesForChildCompositor(
-    TransferableResourceArray* array) {
+    ReturnedResourceArray* array) {
   DCHECK(array->empty());
   array->clear();
 
diff --git a/cc/layers/delegated_renderer_layer.h b/cc/layers/delegated_renderer_layer.h
index 3f5280e..f16217b 100644
--- a/cc/layers/delegated_renderer_layer.h
+++ b/cc/layers/delegated_renderer_layer.h
@@ -7,7 +7,7 @@
 
 #include "cc/base/cc_export.h"
 #include "cc/layers/layer.h"
-#include "cc/resources/transferable_resource.h"
+#include "cc/resources/returned_resource.h"
 
 namespace cc {
 
@@ -34,7 +34,7 @@ class CC_EXPORT DelegatedRendererLayer : public Layer {
 
   // Passes ownership of any unused resources that had been given by the child
   // compositor to the given array, so they can be given back to the child.
-  void TakeUnusedResourcesForChildCompositor(TransferableResourceArray* array);
+  void TakeUnusedResourcesForChildCompositor(ReturnedResourceArray* array);
 
   virtual bool BlocksPendingCommit() const OVERRIDE;
 
@@ -47,7 +47,7 @@ class CC_EXPORT DelegatedRendererLayer : public Layer {
   gfx::RectF damage_in_frame_;
   gfx::Size frame_size_;
   gfx::Size display_size_;
-  TransferableResourceArray unused_resources_for_child_compositor_;
+  ReturnedResourceArray unused_resources_for_child_compositor_;
 
   DelegatedRendererLayerClient* client_;
 
diff --git a/cc/layers/delegated_renderer_layer_impl.cc b/cc/layers/delegated_renderer_layer_impl.cc
index 2dfdac6..426dcbb 100644
--- a/cc/layers/delegated_renderer_layer_impl.cc
+++ b/cc/layers/delegated_renderer_layer_impl.cc
@@ -145,7 +145,7 @@ void DelegatedRendererLayerImpl::SetFrameData(
 }
 
 void DelegatedRendererLayerImpl::CollectUnusedResources(
-    TransferableResourceArray* resources_for_ack) {
+    ReturnedResourceArray* resources_for_ack) {
   CreateChildIdIfNeeded();
   DCHECK(child_id_);
 
@@ -163,7 +163,7 @@ void DelegatedRendererLayerImpl::CollectUnusedResources(
     if (!resource_is_in_current_frame && !resource_is_in_use)
       unused_resources.push_back(it->second);
   }
-  resource_provider->PrepareSendToChild(
+  resource_provider->PrepareSendReturnsToChild(
       child_id_, unused_resources, resources_for_ack);
 }
 
diff --git a/cc/layers/delegated_renderer_layer_impl.h b/cc/layers/delegated_renderer_layer_impl.h
index 9cfdcb6..89b2537 100644
--- a/cc/layers/delegated_renderer_layer_impl.h
+++ b/cc/layers/delegated_renderer_layer_impl.h
@@ -43,7 +43,7 @@ class CC_EXPORT DelegatedRendererLayerImpl : public LayerImpl {
   void SetFrameData(scoped_ptr<DelegatedFrameData> frame_data,
                     gfx::RectF damage_in_frame);
 
-  void CollectUnusedResources(TransferableResourceArray* resources_for_ack);
+  void CollectUnusedResources(ReturnedResourceArray* resources_for_ack);
 
   void SetDisplaySize(gfx::Size size);
 
diff --git a/cc/layers/texture_layer_unittest.cc b/cc/layers/texture_layer_unittest.cc
index 46f9d51..8fb2a15 100644
--- a/cc/layers/texture_layer_unittest.cc
+++ b/cc/layers/texture_layer_unittest.cc
@@ -10,6 +10,7 @@
 #include "cc/debug/test_web_graphics_context_3d.h"
 #include "cc/layers/texture_layer_client.h"
 #include "cc/layers/texture_layer_impl.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_client.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
@@ -785,7 +786,9 @@ TEST_F(TextureLayerImplWithMailboxTest, TestCallbackOnInUseResource) {
   EXPECT_CALL(test_data_.mock_callback_,
               Release(test_data_.mailbox_name1_, _, false))
       .Times(1);
-  provider->ReceiveFromParent(list);
+  ReturnedResourceArray returned;
+  TransferableResource::ReturnResources(list, &returned);
+  provider->ReceiveReturnsFromParent(returned);
 }
 
 // Check that ClearClient correctly clears the state so that the impl side
diff --git a/cc/output/compositor_frame_ack.h b/cc/output/compositor_frame_ack.h
index 276ecf0..943a206 100644
--- a/cc/output/compositor_frame_ack.h
+++ b/cc/output/compositor_frame_ack.h
@@ -8,7 +8,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "cc/base/cc_export.h"
 #include "cc/output/gl_frame_data.h"
-#include "cc/resources/transferable_resource.h"
+#include "cc/resources/returned_resource.h"
 
 namespace cc {
 
@@ -17,7 +17,7 @@ class CC_EXPORT CompositorFrameAck {
   CompositorFrameAck();
   ~CompositorFrameAck();
 
-  TransferableResourceArray resources;
+  ReturnedResourceArray resources;
   scoped_ptr<GLFrameData> gl_frame_data;
   unsigned last_software_frame_id;
 
diff --git a/cc/output/delegating_renderer.cc b/cc/output/delegating_renderer.cc
index be8ab03..226fddb 100644
--- a/cc/output/delegating_renderer.cc
+++ b/cc/output/delegating_renderer.cc
@@ -168,7 +168,7 @@ void DelegatingRenderer::GetFramebufferPixels(void* pixels, gfx::Rect rect) {
 
 void DelegatingRenderer::ReceiveSwapBuffersAck(
     const CompositorFrameAck& ack) {
-  resource_provider_->ReceiveFromParent(ack.resources);
+  resource_provider_->ReceiveReturnsFromParent(ack.resources);
 }
 
 bool DelegatingRenderer::IsContextLost() {
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index b39908a..ff339e9 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -14,6 +14,7 @@
 #include "base/strings/string_util.h"
 #include "cc/output/gl_renderer.h"  // For the GLC() macro.
 #include "cc/resources/platform_color.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/resources/transferable_resource.h"
 #include "cc/scheduler/texture_uploader.h"
 #include "gpu/GLES2/gl2extchromium.h"
@@ -183,10 +184,7 @@ ResourceProvider::~ResourceProvider() {
 }
 
 bool ResourceProvider::InUseByConsumer(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   return resource->lock_for_read_count > 0 || resource->exported_count > 0;
 }
 
@@ -377,10 +375,7 @@ void ResourceProvider::DeleteResourceInternal(ResourceMap::iterator it,
 
 ResourceProvider::ResourceType ResourceProvider::GetResourceType(
     ResourceId id) {
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-  return resource->type;
+  return GetResource(id)->type;
 }
 
 void ResourceProvider::SetPixels(ResourceId id,
@@ -388,10 +383,7 @@ void ResourceProvider::SetPixels(ResourceId id,
                                  gfx::Rect image_rect,
                                  gfx::Rect source_rect,
                                  gfx::Vector2d dest_offset) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->locked_for_write);
   DCHECK(!resource->lock_for_read_count);
   DCHECK(!resource->external);
@@ -493,11 +485,15 @@ bool ResourceProvider::ShallowFlushIfSupported() {
   return true;
 }
 
-const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
+ResourceProvider::Resource* ResourceProvider::GetResource(ResourceId id) {
   DCHECK(thread_checker_.CalledOnValidThread());
   ResourceMap::iterator it = resources_.find(id);
   CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  return &it->second;
+}
+
+const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
+  Resource* resource = GetResource(id);
   DCHECK(!resource->locked_for_write ||
          resource->set_pixels_completion_forced) <<
       "locked for write: " << resource->locked_for_write <<
@@ -533,10 +529,7 @@ const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
 }
 
 void ResourceProvider::UnlockForRead(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK_GT(resource->lock_for_read_count, 0);
   DCHECK_EQ(resource->exported_count, 0);
   resource->lock_for_read_count--;
@@ -544,10 +537,7 @@ void ResourceProvider::UnlockForRead(ResourceId id) {
 
 const ResourceProvider::Resource* ResourceProvider::LockForWrite(
     ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->locked_for_write);
   DCHECK(!resource->lock_for_read_count);
   DCHECK_EQ(resource->exported_count, 0);
@@ -560,10 +550,7 @@ const ResourceProvider::Resource* ResourceProvider::LockForWrite(
 }
 
 bool ResourceProvider::CanLockForWrite(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   return !resource->locked_for_write &&
       !resource->lock_for_read_count &&
       !resource->exported_count &&
@@ -572,10 +559,7 @@ bool ResourceProvider::CanLockForWrite(ResourceId id) {
 }
 
 void ResourceProvider::UnlockForWrite(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(resource->locked_for_write);
   DCHECK_EQ(resource->exported_count, 0);
   DCHECK(!resource->external);
@@ -820,9 +804,10 @@ void ResourceProvider::PrepareSendToParent(const ResourceIdArray& resources,
   }
 }
 
-void ResourceProvider::PrepareSendToChild(int child,
-                                          const ResourceIdArray& resources,
-                                          TransferableResourceArray* list) {
+void ResourceProvider::PrepareSendReturnsToChild(
+    int child,
+    const ResourceIdArray& resources,
+    ReturnedResourceArray* list) {
   DCHECK(thread_checker_.CalledOnValidThread());
   WebGraphicsContext3D* context3d = Context3d();
   if (!context3d || !context3d->makeContextCurrent()) {
@@ -832,27 +817,31 @@ void ResourceProvider::PrepareSendToChild(int child,
   Child& child_info = children_.find(child)->second;
   bool need_sync_point = false;
   for (ResourceIdArray::const_iterator it = resources.begin();
-       it != resources.end();
-       ++it) {
-    TransferableResource resource;
-    TransferResource(context3d, *it, &resource);
-    if (!resource.sync_point)
-      need_sync_point = true;
+       it != resources.end(); ++it) {
+    Resource* resource = GetResource(*it);
+    DCHECK(!resource->locked_for_write);
+    DCHECK(!resource->lock_for_read_count);
     DCHECK(child_info.parent_to_child_map.find(*it) !=
            child_info.parent_to_child_map.end());
-    resource.id = child_info.parent_to_child_map[*it];
+
+    ReturnedResource returned;
+    returned.id = child_info.parent_to_child_map[*it];
+    returned.filter = resource->filter;
+    returned.sync_point = resource->mailbox.sync_point();
+    if (!returned.sync_point)
+      need_sync_point = true;
+    returned.count = resource->imported_count;
+    list->push_back(returned);
+
     child_info.parent_to_child_map.erase(*it);
-    child_info.child_to_parent_map.erase(resource.id);
-    for (int i = 0; i < resources_[*it].imported_count; ++i)
-      list->push_back(resource);
+    child_info.child_to_parent_map.erase(returned.id);
     resources_[*it].imported_count = 0;
     DeleteResource(*it);
   }
   if (need_sync_point) {
     unsigned int sync_point = context3d->insertSyncPoint();
-    for (TransferableResourceArray::iterator it = list->begin();
-         it != list->end();
-         ++it) {
+    for (ReturnedResourceArray::iterator it = list->begin();
+         it != list->end(); ++it) {
       if (!it->sync_point)
         it->sync_point = sync_point;
     }
@@ -903,26 +892,25 @@ void ResourceProvider::ReceiveFromChild(
   }
 }
 
-void ResourceProvider::ReceiveFromParent(
-    const TransferableResourceArray& resources) {
+void ResourceProvider::ReceiveReturnsFromParent(
+    const ReturnedResourceArray& resources) {
   DCHECK(thread_checker_.CalledOnValidThread());
   WebGraphicsContext3D* context3d = Context3d();
   if (!context3d || !context3d->makeContextCurrent()) {
     // TODO(skaslev): Implement this path for software compositing.
     return;
   }
-  for (TransferableResourceArray::const_iterator it = resources.begin();
+  for (ReturnedResourceArray::const_iterator it = resources.begin();
        it != resources.end();
        ++it) {
     ResourceMap::iterator map_iterator = resources_.find(it->id);
     DCHECK(map_iterator != resources_.end());
     Resource* resource = &map_iterator->second;
-    DCHECK_GT(resource->exported_count, 0);
-    --resource->exported_count;
+    CHECK_GE(resource->exported_count, it->count);
+    resource->exported_count -= it->count;
     if (resource->exported_count)
       continue;
     resource->filter = it->filter;
-    DCHECK(resource->mailbox.ContainsMailbox(it->mailbox));
     if (resource->gl_id) {
       if (it->sync_point)
         GLC(context3d, context3d->waitSyncPoint(it->sync_point));
@@ -939,10 +927,7 @@ void ResourceProvider::ReceiveFromParent(
 void ResourceProvider::TransferResource(WebGraphicsContext3D* context,
                                         ResourceId id,
                                         TransferableResource* resource) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* source = &it->second;
+  Resource* source = GetResource(id);
   DCHECK(!source->locked_for_write);
   DCHECK(!source->lock_for_read_count);
   DCHECK(!source->external || (source->external && source->mailbox.IsValid()));
@@ -974,10 +959,7 @@ void ResourceProvider::TransferResource(WebGraphicsContext3D* context,
 }
 
 void ResourceProvider::AcquirePixelBuffer(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
   DCHECK(!resource->image_id);
@@ -1007,10 +989,7 @@ void ResourceProvider::AcquirePixelBuffer(ResourceId id) {
 }
 
 void ResourceProvider::ReleasePixelBuffer(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
   DCHECK(!resource->image_id);
@@ -1052,10 +1031,7 @@ void ResourceProvider::ReleasePixelBuffer(ResourceId id) {
 }
 
 uint8_t* ResourceProvider::MapPixelBuffer(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
   DCHECK(!resource->image_id);
@@ -1083,10 +1059,7 @@ uint8_t* ResourceProvider::MapPixelBuffer(ResourceId id) {
 }
 
 void ResourceProvider::UnmapPixelBuffer(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
   DCHECK(!resource->image_id);
@@ -1158,10 +1131,7 @@ void ResourceProvider::UnbindForSampling(
 }
 
 void ResourceProvider::BeginSetPixels(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(!resource->pending_set_pixels);
 
   LazyCreate(resource);
@@ -1226,10 +1196,7 @@ void ResourceProvider::BeginSetPixels(ResourceId id) {
 }
 
 void ResourceProvider::ForceSetPixelsToComplete(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(resource->locked_for_write);
   DCHECK(resource->pending_set_pixels);
   DCHECK(!resource->set_pixels_completion_forced);
@@ -1245,10 +1212,7 @@ void ResourceProvider::ForceSetPixelsToComplete(ResourceId id) {
 }
 
 bool ResourceProvider::DidSetPixelsComplete(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   DCHECK(resource->locked_for_write);
   DCHECK(resource->pending_set_pixels);
 
@@ -1272,10 +1236,7 @@ bool ResourceProvider::DidSetPixelsComplete(ResourceId id) {
 }
 
 void ResourceProvider::CreateForTesting(ResourceId id) {
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-  LazyCreate(resource);
+  LazyCreate(GetResource(id));
 }
 
 void ResourceProvider::LazyCreate(Resource* resource) {
@@ -1301,10 +1262,7 @@ void ResourceProvider::LazyCreate(Resource* resource) {
 }
 
 void ResourceProvider::AllocateForTesting(ResourceId id) {
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-  LazyAllocate(resource);
+  LazyAllocate(GetResource(id));
 }
 
 void ResourceProvider::LazyAllocate(Resource* resource) {
@@ -1341,19 +1299,12 @@ void ResourceProvider::LazyAllocate(Resource* resource) {
 
 void ResourceProvider::EnableReadLockFences(ResourceProvider::ResourceId id,
                                             bool enable) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
+  Resource* resource = GetResource(id);
   resource->enable_read_lock_fences = enable;
 }
 
 void ResourceProvider::AcquireImage(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
 
@@ -1373,11 +1324,7 @@ void ResourceProvider::AcquireImage(ResourceId id) {
 }
 
 void ResourceProvider::ReleaseImage(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
 
@@ -1392,11 +1339,7 @@ void ResourceProvider::ReleaseImage(ResourceId id) {
 }
 
 uint8_t* ResourceProvider::MapImage(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-
+  Resource* resource = GetResource(id);
   DCHECK(ReadLockFenceHasPassed(resource));
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
@@ -1415,11 +1358,7 @@ uint8_t* ResourceProvider::MapImage(ResourceId id) {
 }
 
 void ResourceProvider::UnmapImage(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
 
@@ -1431,11 +1370,7 @@ void ResourceProvider::UnmapImage(ResourceId id) {
 }
 
 int ResourceProvider::GetImageStride(ResourceId id) {
-  DCHECK(thread_checker_.CalledOnValidThread());
-  ResourceMap::iterator it = resources_.find(id);
-  CHECK(it != resources_.end());
-  Resource* resource = &it->second;
-
+  Resource* resource = GetResource(id);
   DCHECK(!resource->external);
   DCHECK_EQ(resource->exported_count, 0);
 
diff --git a/cc/resources/resource_provider.h b/cc/resources/resource_provider.h
index c434b3a..73b6e2b 100644
--- a/cc/resources/resource_provider.h
+++ b/cc/resources/resource_provider.h
@@ -152,9 +152,9 @@ class CC_EXPORT ResourceProvider {
   // Resources are removed from the ResourceProvider. Note: the resource IDs
   // passed are in the parent namespace and will be translated to the child
   // namespace when returned.
-  void PrepareSendToChild(int child,
-                          const ResourceIdArray& resources,
-                          TransferableResourceArray* transferable_resources);
+  void PrepareSendReturnsToChild(int child,
+                                 const ResourceIdArray& resources,
+                                 ReturnedResourceArray* returned_resources);
 
   // Receives resources from a child, moving them from mailboxes. Resource IDs
   // passed are in the child namespace, and will be translated to the parent
@@ -168,8 +168,8 @@ class CC_EXPORT ResourceProvider {
   // IDs passed are in the child namespace.
   // NOTE: if the sync_point is set on any TransferableResource, this will
   // wait on it.
-  void ReceiveFromParent(
-      const TransferableResourceArray& transferable_resources);
+  void ReceiveReturnsFromParent(
+      const ReturnedResourceArray& transferable_resources);
 
   // The following lock classes are part of the ResourceProvider API and are
   // needed to read and write the resource contents. The user must ensure
@@ -392,6 +392,7 @@ class CC_EXPORT ResourceProvider {
 
   void CleanUpGLIfNeeded();
 
+  Resource* GetResource(ResourceId id);
   const Resource* LockForRead(ResourceId id);
   void UnlockForRead(ResourceId id);
   const Resource* LockForWrite(ResourceId id);
diff --git a/cc/resources/resource_provider_unittest.cc b/cc/resources/resource_provider_unittest.cc
index 83e90b4..dec66d6 100644
--- a/cc/resources/resource_provider_unittest.cc
+++ b/cc/resources/resource_provider_unittest.cc
@@ -13,6 +13,7 @@
 #include "cc/base/scoped_ptr_deque.h"
 #include "cc/debug/test_web_graphics_context_3d.h"
 #include "cc/output/output_surface.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/test/fake_output_surface.h"
 #include "cc/test/fake_output_surface_client.h"
 #include "gpu/GLES2/gl2extchromium.h"
@@ -602,7 +603,9 @@ TEST_P(ResourceProviderTest, TransferResources) {
                                                  &list);
     EXPECT_EQ(1u, list.size());
     EXPECT_EQ(id1, list[0].id);
-    child_resource_provider->ReceiveFromParent(list);
+    ReturnedResourceArray returned;
+    TransferableResource::ReturnResources(list, &returned);
+    child_resource_provider->ReceiveReturnsFromParent(returned);
     // id1 was exported twice, we returned it only once, it should still be
     // in-use.
     EXPECT_TRUE(child_resource_provider->InUseByConsumer(id1));
@@ -612,13 +615,13 @@ TEST_P(ResourceProviderTest, TransferResources) {
     ResourceProvider::ResourceIdArray resource_ids_to_transfer;
     resource_ids_to_transfer.push_back(mapped_id1);
     resource_ids_to_transfer.push_back(mapped_id2);
-    TransferableResourceArray list;
-    resource_provider_->PrepareSendToChild(
+    ReturnedResourceArray list;
+    resource_provider_->PrepareSendReturnsToChild(
         child_id, resource_ids_to_transfer, &list);
     ASSERT_EQ(2u, list.size());
     EXPECT_NE(0u, list[0].sync_point);
     EXPECT_NE(0u, list[1].sync_point);
-    child_resource_provider->ReceiveFromParent(list);
+    child_resource_provider->ReceiveReturnsFromParent(list);
   }
   EXPECT_FALSE(child_resource_provider->InUseByConsumer(id1));
   EXPECT_FALSE(child_resource_provider->InUseByConsumer(id2));
@@ -711,12 +714,12 @@ TEST_P(ResourceProviderTest, DeleteTransferredResources) {
     EXPECT_NE(0u, mapped_id);
     ResourceProvider::ResourceIdArray resource_ids_to_transfer;
     resource_ids_to_transfer.push_back(mapped_id);
-    TransferableResourceArray list;
-    resource_provider_->PrepareSendToChild(
+    ReturnedResourceArray list;
+    resource_provider_->PrepareSendReturnsToChild(
         child_id, resource_ids_to_transfer, &list);
     ASSERT_EQ(1u, list.size());
     EXPECT_NE(0u, list[0].sync_point);
-    child_resource_provider->ReceiveFromParent(list);
+    child_resource_provider->ReceiveReturnsFromParent(list);
   }
   EXPECT_EQ(0u, child_resource_provider->num_resources());
 }
@@ -783,12 +786,12 @@ TEST_P(ResourceProviderTest, TextureFilters) {
     // Transfer resources back from the parent to the child.
     ResourceProvider::ResourceIdArray resource_ids_to_transfer;
     resource_ids_to_transfer.push_back(mapped_id);
-    TransferableResourceArray list;
-    resource_provider_->PrepareSendToChild(
+    ReturnedResourceArray list;
+    resource_provider_->PrepareSendReturnsToChild(
         child_id, resource_ids_to_transfer, &list);
     ASSERT_EQ(1u, list.size());
     EXPECT_EQ(static_cast<unsigned>(GL_LINEAR), list[0].filter);
-    child_resource_provider->ReceiveFromParent(list);
+    child_resource_provider->ReceiveReturnsFromParent(list);
   }
   EXPECT_EQ(static_cast<unsigned>(GL_LINEAR),
             GetResourceFilter(child_resource_provider.get(),
@@ -861,7 +864,9 @@ TEST_P(ResourceProviderTest, TransferMailboxResources) {
 
     // Receive the resource, then delete it, expect the sync points to be
     // consistent.
-    resource_provider_->ReceiveFromParent(list);
+    ReturnedResourceArray returned;
+    TransferableResource::ReturnResources(list, &returned);
+    resource_provider_->ReceiveReturnsFromParent(returned);
     EXPECT_EQ(1, context()->texture_count());
     EXPECT_EQ(0u, release_sync_point);
 
@@ -910,7 +915,9 @@ TEST_P(ResourceProviderTest, TransferMailboxResources) {
 
     // Then receive the resource which should release the mailbox, expect the
     // sync points to be consistent.
-    resource_provider_->ReceiveFromParent(list);
+    ReturnedResourceArray returned;
+    TransferableResource::ReturnResources(list, &returned);
+    resource_provider_->ReceiveReturnsFromParent(returned);
     EXPECT_LE(list[0].sync_point, release_sync_point);
     EXPECT_FALSE(lost_resource);
   }
diff --git a/cc/resources/returned_resource.h b/cc/resources/returned_resource.h
new file mode 100644
index 0000000..aa6b99a
--- /dev/null
+++ b/cc/resources/returned_resource.h
@@ -0,0 +1,27 @@
+// Copyright 2013 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.
+
+#ifndef CC_RESOURCES_RETURNED_RESOURCE_H_
+#define CC_RESOURCES_RETURNED_RESOURCE_H_
+
+#include <vector>
+
+#include "base/basictypes.h"
+#include "cc/base/cc_export.h"
+
+namespace cc {
+
+struct CC_EXPORT ReturnedResource {
+  ReturnedResource() : id(0), sync_point(0), filter(0), count(0) {}
+  unsigned id;
+  unsigned sync_point;
+  uint32 filter;
+  int count;
+};
+
+typedef std::vector<ReturnedResource> ReturnedResourceArray;
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_RETURNED_RESOURCE_H_
diff --git a/cc/resources/transferable_resource.cc b/cc/resources/transferable_resource.cc
index be2be1a..9e90696 100644
--- a/cc/resources/transferable_resource.cc
+++ b/cc/resources/transferable_resource.cc
@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/logging.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/resources/transferable_resource.h"
 
 namespace cc {
@@ -17,4 +18,22 @@ TransferableResource::TransferableResource()
 TransferableResource::~TransferableResource() {
 }
 
+ReturnedResource TransferableResource::ToReturnedResource() const {
+  ReturnedResource returned;
+  returned.id = id;
+  returned.sync_point = sync_point;
+  returned.filter = filter;
+  returned.count = 1;
+  return returned;
+}
+
+// static
+void TransferableResource::ReturnResources(
+    const TransferableResourceArray& input,
+    ReturnedResourceArray* output) {
+  for (TransferableResourceArray::const_iterator it = input.begin();
+       it != input.end(); ++it)
+    output->push_back(it->ToReturnedResource());
+}
+
 }  // namespace cc
diff --git a/cc/resources/transferable_resource.h b/cc/resources/transferable_resource.h
index 5c979433..be6902c 100644
--- a/cc/resources/transferable_resource.h
+++ b/cc/resources/transferable_resource.h
@@ -14,10 +14,19 @@
 
 namespace cc {
 
+struct ReturnedResource;
+typedef std::vector<ReturnedResource> ReturnedResourceArray;
+struct TransferableResource;
+typedef std::vector<TransferableResource> TransferableResourceArray;
+
 struct CC_EXPORT TransferableResource {
   TransferableResource();
   ~TransferableResource();
 
+  ReturnedResource ToReturnedResource() const;
+  static void ReturnResources(const TransferableResourceArray& input,
+                              ReturnedResourceArray* output);
+
   unsigned id;
   unsigned sync_point;
   uint32 format;
@@ -26,8 +35,6 @@ struct CC_EXPORT TransferableResource {
   gpu::Mailbox mailbox;
 };
 
-typedef std::vector<TransferableResource> TransferableResourceArray;
-
 }  // namespace cc
 
 #endif  // CC_RESOURCES_TRANSFERABLE_RESOURCE_H_
diff --git a/cc/test/fake_delegated_renderer_layer_impl.cc b/cc/test/fake_delegated_renderer_layer_impl.cc
index c6a639e..782bc1c 100644
--- a/cc/test/fake_delegated_renderer_layer_impl.cc
+++ b/cc/test/fake_delegated_renderer_layer_impl.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "cc/output/delegated_frame_data.h"
 #include "cc/quads/draw_quad.h"
+#include "cc/resources/returned_resource.h"
 
 namespace cc {
 
@@ -45,7 +46,7 @@ void FakeDelegatedRendererLayerImpl::SetFrameDataForRenderPasses(
       pass->quad_list[j]->IterateResources(add_resource_to_frame_callback);
   }
 
-  TransferableResourceArray resources_for_ack;
+  ReturnedResourceArray resources_for_ack;
   SetFrameData(delegated_frame.Pass(), gfx::RectF());
   CollectUnusedResources(&resources_for_ack);
 }
diff --git a/cc/test/fake_output_surface.cc b/cc/test/fake_output_surface.cc
index 32367fd..bc94f19 100644
--- a/cc/test/fake_output_surface.cc
+++ b/cc/test/fake_output_surface.cc
@@ -8,6 +8,7 @@
 #include "base/message_loop/message_loop.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/output/output_surface_client.h"
+#include "cc/resources/returned_resource.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cc {
@@ -126,7 +127,7 @@ void FakeOutputSurface::ReturnResource(unsigned id, CompositorFrameAck* ack) {
       break;
   }
   DCHECK(it != resources_held_by_parent_.end());
-  ack->resources.push_back(*it);
+  ack->resources.push_back(it->ToReturnedResource());
   resources_held_by_parent_.erase(it);
 }
 
diff --git a/cc/trees/layer_tree_host_unittest_delegated.cc b/cc/trees/layer_tree_host_unittest_delegated.cc
index f15da5d..721613a 100644
--- a/cc/trees/layer_tree_host_unittest_delegated.cc
+++ b/cc/trees/layer_tree_host_unittest_delegated.cc
@@ -15,6 +15,7 @@
 #include "cc/output/delegated_frame_data.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/texture_draw_quad.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/test/fake_delegated_renderer_layer.h"
 #include "cc/test/fake_delegated_renderer_layer_impl.h"
 #include "cc/test/fake_output_surface.h"
@@ -26,29 +27,40 @@
 namespace cc {
 namespace {
 
-bool TransferableResourceLower(const TransferableResource& a,
-                               const TransferableResource& b) {
+bool ReturnedResourceLower(const ReturnedResource& a,
+                           const ReturnedResource& b) {
   return a.id < b.id;
 }
 
 // Tests if the list of resources matches an expectation, modulo the order.
-bool ResourcesMatch(TransferableResourceArray actual,
+bool ResourcesMatch(ReturnedResourceArray actual,
                     unsigned* expected,
                     size_t expected_count) {
-  EXPECT_EQ(expected_count, actual.size());
-  if (expected_count != actual.size())
-    return false;
-
-  std::sort(actual.begin(), actual.end(), TransferableResourceLower);
+  std::sort(actual.begin(), actual.end(), ReturnedResourceLower);
   std::sort(expected, expected + expected_count);
-  bool result = true;
-  for (size_t i = 0; i < expected_count; ++i) {
-    EXPECT_EQ(actual[i].id, expected[i]);
-    if (actual[i].id != expected[i])
-      result = false;
+  size_t actual_index = 0;
+
+  // for each element of the expected array, count off one of the actual array
+  // (after checking it matches).
+  for (size_t expected_index = 0; expected_index < expected_count;
+       ++expected_index) {
+    EXPECT_LT(actual_index, actual.size());
+    if (actual_index >= actual.size())
+      return false;
+    EXPECT_EQ(actual[actual_index].id, expected[expected_index]);
+    if (actual[actual_index].id != expected[expected_index])
+      return false;
+    EXPECT_GT(actual[actual_index].count, 0);
+    if (actual[actual_index].count <= 0) {
+      return false;
+    } else {
+      --actual[actual_index].count;
+      if (actual[actual_index].count == 0)
+        ++actual_index;
+    }
   }
-
-  return result;
+  EXPECT_EQ(actual_index, actual.size());
+  return actual_index == actual.size();
 }
 
 #define EXPECT_RESOURCES(expected, actual) \
@@ -531,7 +543,7 @@ class LayerTreeHostDelegatedTestMergeResources
 
     // The resource 999 from frame1 is returned since it is still on the main
     // thread.
-    TransferableResourceArray returned_resources;
+    ReturnedResourceArray returned_resources;
     delegated_->TakeUnusedResourcesForChildCompositor(&returned_resources);
     {
       unsigned expected[] = {999};
@@ -627,7 +639,7 @@ class LayerTreeHostDelegatedTestReturnUnusedResources
 
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -691,7 +703,7 @@ class LayerTreeHostDelegatedTestReturnUnusedResources
     }
 
     // Resource are never immediately released.
-    TransferableResourceArray empty_resources;
+    ReturnedResourceArray empty_resources;
     delegated_->TakeUnusedResourcesForChildCompositor(&empty_resources);
     EXPECT_TRUE(empty_resources.empty());
   }
@@ -716,7 +728,7 @@ class LayerTreeHostDelegatedTestReusedResources
 
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -792,7 +804,7 @@ class LayerTreeHostDelegatedTestFrameBeforeAck
 
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -900,7 +912,7 @@ class LayerTreeHostDelegatedTestFrameBeforeTakeResources
 
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -1033,7 +1045,7 @@ class LayerTreeHostDelegatedTestBadFrame
 
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -1204,7 +1216,7 @@ class LayerTreeHostDelegatedTestUnnamedResource
 
   virtual void DidCommit() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -1263,7 +1275,7 @@ class LayerTreeHostDelegatedTestDontLeakResource
 
   virtual void DidCommit() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -1347,7 +1359,7 @@ class LayerTreeHostDelegatedTestResourceSentToParent
  public:
   virtual void DidCommitAndDrawFrame() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
@@ -1462,7 +1474,7 @@ class LayerTreeHostDelegatedTestCommitWithoutTake
 
   virtual void DidCommit() OVERRIDE {
     scoped_ptr<DelegatedFrameData> frame;
-    TransferableResourceArray resources;
+    ReturnedResourceArray resources;
 
     int next_source_frame_number = layer_tree_host()->source_frame_number();
     switch (next_source_frame_number) {
diff --git a/content/browser/renderer_host/render_widget_host_impl.cc b/content/browser/renderer_host/render_widget_host_impl.cc
index edd21fe..289879d 100644
--- a/content/browser/renderer_host/render_widget_host_impl.cc
+++ b/content/browser/renderer_host/render_widget_host_impl.cc
@@ -1482,7 +1482,9 @@ bool RenderWidgetHostImpl::OnSwapCompositorFrame(
       ack.gl_frame_data = frame->gl_frame_data.Pass();
       ack.gl_frame_data->sync_point = 0;
     } else if (frame->delegated_frame_data) {
-      ack.resources.swap(frame->delegated_frame_data->resource_list);
+      cc::TransferableResource::ReturnResources(
+          frame->delegated_frame_data->resource_list,
+          &ack.resources);
     } else if (frame->software_frame_data) {
       ack.last_software_frame_id = frame->software_frame_data->id;
     }
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 8c52017..ea737b4 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -1448,7 +1448,8 @@ void RenderWidgetHostViewAura::SwapDelegatedFrame(
   }
   if (ShouldSkipFrame(frame_size_in_dip)) {
     cc::CompositorFrameAck ack;
-    ack.resources.swap(frame_data->resource_list);
+    cc::TransferableResource::ReturnResources(frame_data->resource_list,
+                                              &ack.resources);
     RenderWidgetHostImpl::SendSwapCompositorFrameAck(
         host_->GetRoutingID(), output_surface_id,
         host_->GetProcess()->GetID(), ack);
diff --git a/content/common/cc_messages.h b/content/common/cc_messages.h
index 380d453..ca4ddc1 100644
--- a/content/common/cc_messages.h
+++ b/content/common/cc_messages.h
@@ -21,6 +21,7 @@
 #include "cc/quads/texture_draw_quad.h"
 #include "cc/quads/tile_draw_quad.h"
 #include "cc/quads/yuv_video_draw_quad.h"
+#include "cc/resources/returned_resource.h"
 #include "cc/resources/transferable_resource.h"
 #include "content/common/content_export.h"
 #include "gpu/ipc/gpu_command_buffer_traits.h"
@@ -221,6 +222,13 @@ IPC_STRUCT_TRAITS_BEGIN(cc::TransferableResource)
   IPC_STRUCT_TRAITS_MEMBER(mailbox)
 IPC_STRUCT_TRAITS_END()
 
+IPC_STRUCT_TRAITS_BEGIN(cc::ReturnedResource)
+  IPC_STRUCT_TRAITS_MEMBER(id)
+  IPC_STRUCT_TRAITS_MEMBER(sync_point)
+  IPC_STRUCT_TRAITS_MEMBER(filter)
+  IPC_STRUCT_TRAITS_MEMBER(count)
+IPC_STRUCT_TRAITS_END()
+
 IPC_STRUCT_TRAITS_BEGIN(cc::BeginFrameArgs)
   IPC_STRUCT_TRAITS_MEMBER(frame_time)
   IPC_STRUCT_TRAITS_MEMBER(deadline)
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 6c0fde3..f5bf42c 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -552,7 +552,7 @@ void Layer::SetDelegatedFrame(scoped_ptr<cc::DelegatedFrameData> frame,
 }
 
 void Layer::TakeUnusedResourcesForChildCompositor(
-    cc::TransferableResourceArray* list) {
+    cc::ReturnedResourceArray* list) {
   if (delegated_renderer_layer_.get())
     delegated_renderer_layer_->TakeUnusedResourcesForChildCompositor(list);
 }
diff --git a/ui/compositor/layer.h b/ui/compositor/layer.h
index aa78d93..cd640b1 100644
--- a/ui/compositor/layer.h
+++ b/ui/compositor/layer.h
@@ -38,8 +38,8 @@ class Layer;
 class ResourceUpdateQueue;
 class SolidColorLayer;
 class TextureLayer;
-struct TransferableResource;
-typedef std::vector<TransferableResource> TransferableResourceArray;
+struct ReturnedResource;
+typedef std::vector<ReturnedResource> ReturnedResourceArray;
 }
 
 namespace ui {
@@ -267,7 +267,7 @@ class COMPOSITOR_EXPORT Layer
 
   // Gets unused resources to recycle to the child compositor.
   void TakeUnusedResourcesForChildCompositor(
-      cc::TransferableResourceArray* array);
+      cc::ReturnedResourceArray* array);
 
   // Sets the layer's fill color.  May only be called for LAYER_SOLID_COLOR.
   void SetColor(SkColor color);