Reland r206537 - cc: Don't return mailboxes if the TextureLayer is removed from the tree.

cc/layers/texture_layer.h

Index: cc/layers/texture_layer.h
diff --git a/cc/layers/texture_layer.h b/cc/layers/texture_layer.h
index 6de1ea49efeee466ad273c2de98b89c817f01f99..5193fae45087b4174b35efdeca097acdefe1a296 100644
--- a/cc/layers/texture_layer.h
+++ b/cc/layers/texture_layer.h
@@ -14,6 +14,10 @@
 
 namespace WebKit { class WebGraphicsContext3D; }
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace cc {
 
 class TextureLayerClient;
@@ -84,6 +88,35 @@ class CC_EXPORT TextureLayer : public Layer {
   virtual ~TextureLayer();
 
  private:
+  class MailboxHolder : public base::RefCounted<MailboxHolder> {
+   public:
+    explicit MailboxHolder(const TextureMailbox& mailbox);
+
+    const TextureMailbox& mailbox() const { return mailbox_; }
+    void Return(unsigned sync_point, bool is_lost);
+
+    // Gets a ReleaseCallback that can be called from another thread. Note: this
+    // adds a reference that is only released when the callback is called (as
+    // opposed to a traditional callback which releases the reference on
+    // destruction), so the caller must ensure the callback is called.
+    TextureMailbox::ReleaseCallback GetCallbackForImplThread();
+
+   private:
+    friend class base::RefCounted<MailboxHolder>;
+    ~MailboxHolder();
+    void ReturnAndReleaseOnMainThread(unsigned sync_point, bool is_lost);
+    void ReturnAndReleaseOnImplThread(unsigned sync_point, bool is_lost);
+
+    // Thread safety notes: except for the thread-safe message_loop_, all fields
+    // (including refcount) are only used on the main thread, or on the impl
+    // thread during commit where the main thread is blocked.
+    scoped_refptr<base::MessageLoopProxy> const message_loop_;

[danakj, 2013/06/18 00:53:24]

nit: const first (why const?)

[piman, 2013/06/18 02:10:58]

Done.

+    TextureMailbox mailbox_;
+    unsigned sync_point_;
+    bool is_lost_;
+    DISALLOW_COPY_AND_ASSIGN(MailboxHolder);
+  };
+
   TextureLayerClient* client_;
   bool uses_mailbox_;
 
@@ -98,8 +131,8 @@ class CC_EXPORT TextureLayer : public Layer {
   bool content_committed_;
 
   unsigned texture_id_;
-  TextureMailbox texture_mailbox_;
-  bool own_mailbox_;
+  scoped_refptr<MailboxHolder> holder_;
+  bool needs_set_mailbox_;
 
   DISALLOW_COPY_AND_ASSIGN(TextureLayer);
 };