exo: Recreate Surface resources on context lost.

components/exo/buffer.h

 // Copyright 2015 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 COMPONENTS_EXO_BUFFER_H_
 #define COMPONENTS_EXO_BUFFER_H_
 
 #include <memory>
 
 #include "base/callback.h"
@@ skipping 38 matching lines @@
   // Set the callback to run when the buffer is no longer used by the
   // compositor. The client is free to re-use or destroy this buffer and
   // its backing storage after this has been called.
   void set_release_callback(const base::Closure& release_callback) {
     release_callback_ = release_callback;
   }
 
   // This function can be used to acquire a texture mailbox for the contents of
   // buffer. Returns a release callback on success. The release callback should
   // be called before a new texture mailbox can be acquired unless
-  // |non_client_usage| is true.
+  // |non_client_usage| is true. |detach_callback| receives a callback that
+  // should be called when the buffer is detached from the current surface.
   std::unique_ptr<cc::SingleReleaseCallback> ProduceTextureMailbox(
       cc::TextureMailbox* mailbox,
       bool secure_output_only,
-      bool client_usage);
+      bool client_usage,
+      base::Closure* detach_callback);

[reveman, 2016/06/22 17:15:26]

hm, I see how this works but it took a minute for me to understand it.

Instead of returning a callback here. What do you think about just adding two
functions to the Buffer class, OnAttach+OnDetach and just call those directly
from the Surface class when appropriate? Potentially adding some private
BufferAttachment utility class to exo::Surface to handle the call to OnDetach
automatically. OnAttach/Detach can keep a attachment count and that we can also
improve debug output by logging something when a buffer is attached to two
different surfaces.

[jbauman, 2016/06/22 23:45:48]

Done.

 
   // Returns the size of the buffer.
   gfx::Size GetSize() const;
 
   // Returns a trace value representing the state of the buffer.
   std::unique_ptr<base::trace_event::TracedValue> AsTracedValue() const;
 
  private:
   class Texture;
 
@@ skipping 40 matching lines @@
 
   // The client release callback.
   base::Closure release_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(Buffer);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_BUFFER_H_