Virtual context MakeCurrent tweaks.

content/common/gpu/gpu_command_buffer_stub.cc

 // Copyright (c) 2012 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.
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/hash.h"
 #include "base/shared_memory.h"
@@ skipping 342 matching lines @@
   // destroy it before those.
   scheduler_.reset();
 
   bool have_context = false;
   if (decoder_)
     have_context = decoder_->MakeCurrent();
   FOR_EACH_OBSERVER(DestructionObserver,
                     destruction_observers_,
                     OnWillDestroyStub());
 
-  scoped_refptr<gfx::GLContext> context;
   if (decoder_) {
-    context = decoder_->GetGLContext();
+    // The surface destructor should be called with a current context.
+    // Therefore release the stub's reference before destroying the decoder,
+    // because the latter will release the context.
+    surface_ = NULL;

[epenner, 2013/05/28 22:57:21]

Are you sure this is the last valid reference to the surface? Could decoder_
have one until it is destroyed? It would be nice if we could DCHECK that this is
the last suface reference if we need that to be the case.

[no sievers, 2013/05/28 23:15:32]

Ah good point, I forgot to release the decoder's ref - see updated patch.

Otherwise, I think it's fine if multiple decoders share the surface, because the
last one going away would still make it current. In fact, that shouldn't have
behaved better before my patch. I added the error log now to catch bad usage
cases.

     decoder_->Destroy(have_context);
     decoder_.reset();
   }
 
   command_buffer_.reset();
-
-  // Make sure that context_ is current while we destroy surface_, because
-  // surface_ may have GL resources that it needs to destroy, and will need
-  // context_ to be current in order to not leak these resources.
-  if (context)
-    context->MakeCurrent(surface_.get());
-  surface_ = NULL;
-  if (context)
-    context->ReleaseCurrent(NULL);
 }
 
 void GpuCommandBufferStub::OnInitializeFailed(IPC::Message* reply_message) {
   Destroy();
   GpuCommandBufferMsg_Initialize::WriteReplyParams(reply_message, false);
   Send(reply_message);
 }
 
 void GpuCommandBufferStub::OnInitialize(
     base::SharedMemoryHandle shared_state_handle,
@@ skipping 549 matching lines @@
     if (surface_ && MakeCurrent())
       surface_->SetFrontbufferAllocation(
           allocation.browser_allocation.suggest_have_frontbuffer);
   }
 
   last_memory_allocation_valid_ = true;
   last_memory_allocation_ = allocation;
 }
 
 }  // namespace content