[Reland 1] Pepper takes ownership of a mailbox before passing it to the texture layer.

content/renderer/pepper/pepper_plugin_instance_impl.h

Index: content/renderer/pepper/pepper_plugin_instance_impl.h
diff --git a/content/renderer/pepper/pepper_plugin_instance_impl.h b/content/renderer/pepper/pepper_plugin_instance_impl.h
index da461798a5502d85b77b040a6e0bbc80c3ec0cb0..2ad4318efc701705e3310e60eabdef50e1dbd6ea 100644
--- a/content/renderer/pepper/pepper_plugin_instance_impl.h
+++ b/content/renderer/pepper/pepper_plugin_instance_impl.h
@@ -24,6 +24,7 @@
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/texture_layer_client.h"
+#include "cc/resources/texture_mailbox.h"
 #include "content/common/content_export.h"
 #include "content/public/renderer/pepper_plugin_instance.h"
 #include "content/public/renderer/plugin_instance_throttler.h"
@@ -197,9 +198,17 @@ class CONTENT_EXPORT PepperPluginInstanceImpl
   // slow path can also be triggered if there is an overlapping frame.
   void ScrollRect(int dx, int dy, const gfx::Rect& rect);
 
-  // Commit the backing texture to the screen once the side effects some
-  // rendering up to an offscreen SwapBuffers are visible.
-  void CommitBackingTexture();
+  // Commit the texture mailbox to the screen.
+  void CommitTextureMailbox(const cc::TextureMailbox& texture_mailbox);
+
+  // Passes the committed texture to |texture_layer_| and marks it as in use.
+  void PassCommittedTextureToTextureLayer();
+
+  // Callback when the compositor is finished consuming the committed texture.
+  void FinishedConsumingCommittedTexture(
+      const cc::TextureMailbox& texture_mailbox,
+      const gpu::SyncToken& sync_token,
+      bool is_lost);
 
   // Called when the out-of-process plugin implementing this instance crashed.
   void InstanceCrashed();
@@ -702,6 +711,28 @@ class CONTENT_EXPORT PepperPluginInstanceImpl
   void ConvertRectToDIP(PP_Rect* rect) const;
   void ConvertDIPToViewport(gfx::Rect* rect) const;
 
+  // Each time CommitTextureMailbox() is called, this instance is given
+  // ownership
+  // of a cc::TextureMailbox. This instance always needs to hold on to the most
+  // recently committed cc::TextureMailbox, since UpdateLayer() might require
+  // it.
+  // Since it is possible for a cc::TextureMailbox to be passed to
+  // texture_layer_ more than once, a reference counting mechanism is necessary
+  // to ensure that a cc::TextureMailbox isn't returned until all copies of it
+  // have been released by texture_layer_.
+  //
+  // This method should be called each time a cc::TextureMailbox is passed to
+  // |texture_layer_|. It increments an internal reference count.
+  void IncrementTextureReferenceCount(const cc::TextureMailbox& mailbox);
+
+  // This method should be called each time |texture_layer_| finishes consuming
+  // a cc::TextureMailbox. It decrements an internal reference count. Returns
+  // whether the last reference was removed.
+  bool DecrementTextureReferenceCount(const cc::TextureMailbox& mailbox);
+
+  // Whether a given cc::TextureMailbox is in use by |texture_layer_|.
+  bool IsTextureInUse(const cc::TextureMailbox& mailbox) const;
+
   RenderFrameImpl* render_frame_;
   base::Closure instance_deleted_callback_;
   scoped_refptr<PluginModule> module_;
@@ -933,6 +964,19 @@ class CONTENT_EXPORT PepperPluginInstanceImpl
   // The text that is currently selected in the plugin.
   base::string16 selected_text_;
 
+  // The most recently committed texture. This is kept around in case the layer
+  // needs to be regenerated.
+  cc::TextureMailbox committed_texture_;
+
+  gpu::SyncToken committed_texture_consumed_sync_token_;
+
+  // Holds the number of references |texture_layer_| has to any given
+  // cc::TextureMailbox.
+  // We expect there to be no more than 10 textures in use at a time. A
+  // std::vector will have better performance than a std::map.
+  using TextureMailboxRefCount = std::pair<cc::TextureMailbox, int>;
+  std::vector<TextureMailboxRefCount> texture_ref_counts_;
+
   bool initialized_;
 
   // We use a weak ptr factory for scheduling DidChangeView events so that we