Return overlay resources to renderers in larger batches.

cc/resources/resource_provider.h

Index: cc/resources/resource_provider.h
diff --git a/cc/resources/resource_provider.h b/cc/resources/resource_provider.h
index df3c5b85fb6bf1fa476f80761982df271ce19fa2..8cef6de286abdf9096d4d0b0df9b2ac91884cb72 100644
--- a/cc/resources/resource_provider.h
+++ b/cc/resources/resource_provider.h
@@ -18,6 +18,7 @@
 #include <vector>
 
 #include "base/callback.h"
+#include "base/containers/small_map.h"
 #include "base/macros.h"
 #include "base/memory/linked_ptr.h"
 #include "base/threading/thread_checker.h"
@@ -444,6 +445,19 @@ class CC_EXPORT ResourceProvider
     DISALLOW_COPY_AND_ASSIGN(ScopedWriteLockGpuMemoryBuffer);
   };
 
+  // All resources that are returned to children while an instance of this
+  // class exists will be stored and returned when the instance is destroyed.
+  class CC_EXPORT ScopedBatchReturnResources {
+   public:
+    explicit ScopedBatchReturnResources(ResourceProvider* resource_provider);
+    ~ScopedBatchReturnResources();
+
+   private:
+    ResourceProvider* resource_provider_;
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedBatchReturnResources);
+  };
+
   class Fence : public base::RefCounted<Fence> {
    public:
     Fence() {}
@@ -524,6 +538,8 @@ class CC_EXPORT ResourceProvider
 
   GLenum GetImageTextureTarget(gfx::BufferUsage usage, ResourceFormat format);
 
+  void SetBatchReturnResources(bool aggregate);

[Daniele Castagna, 2017/03/27 13:38:11]

nit: Can this be moved away from the public ResourceProvider API?
Maybe it could be private and friend of the ScopedBatchReturnResources, WDYT?

+
   // base::trace_event::MemoryDumpProvider implementation.
   bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
                     base::trace_event::ProcessMemoryDump* pmd) override;
@@ -774,6 +790,12 @@ class CC_EXPORT ResourceProvider
   std::unique_ptr<TextureIdAllocator> texture_id_allocator_;
   BufferToTextureTargetMap buffer_to_texture_target_map_;
 
+  // Keep track of whether deleted resources should be batched up or returned
+  // immediately.
+  bool batch_return_resources_ = false;
+  // Maps from a child id to the set of resources to be returned to it.
+  base::SmallMap<std::map<int, ResourceIdArray>> batched_returning_resources_;
+
   base::ThreadChecker thread_checker_;
 
   // A process-unique ID used for disambiguating memory dumps from different