cc: Implement shared worker contexts. (v1)

content/common/gpu/client/context_provider_command_buffer.cc

 // Copyright (c) 2013 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 "content/common/gpu/client/context_provider_command_buffer.h"
 
 #include <set>
 #include <vector>
 
 #include "base/callback_helpers.h"
@@ skipping 91 matching lines @@
 
   std::string unique_context_name =
       base::StringPrintf("%s-%p", debug_name_.c_str(), context3d_.get());
   context3d_->traceBeginCHROMIUM("gpu_toplevel", unique_context_name.c_str());
 
   lost_context_callback_proxy_.reset(new LostContextCallbackProxy(this));
   return true;
 }
 
 void ContextProviderCommandBuffer::DetachFromThread() {
+  DCHECK(context3d_);
+  // Invalidate any weak pointers used by the context3d_ to ensure that it's
+  // safe to use and destroy it on a different thread. There's no guarantee
+  // that callbacks such as ContextLost will be delivered after this has been

[danakj, 2015/09/03 18:09:58]

Can you add this to the ContextProvider::DetachFromThread comment too?

+  // called.
+  context3d_->InvalidateWeakPtrsOnCurrentThread();
   context_thread_checker_.DetachFromThread();
 }
 
 gpu::gles2::GLES2Interface* ContextProviderCommandBuffer::ContextGL() {
   DCHECK(context3d_);
   DCHECK(lost_context_callback_proxy_);  // Is bound to thread.
   DCHECK(context_thread_checker_.CalledOnValidThread());
 
   return context3d_->GetImplementation();
 }
@@ skipping 53 matching lines @@
 }
 
 void ContextProviderCommandBuffer::DeleteCachedResources() {
   DCHECK(context_thread_checker_.CalledOnValidThread());
 
   if (gr_context_)
     gr_context_->FreeGpuResources();
 }
 
 void ContextProviderCommandBuffer::OnLostContext() {
-  DCHECK(context_thread_checker_.CalledOnValidThread());
+  // Note: no thread check here as this should not change the thread for which
+  // this context is currently bound. e.g. a worker context might be unbound
+  // and this should not result in it being bound to the current thread.
   {
     base::AutoLock lock(main_thread_lock_);
     if (destroyed_)
       return;
     destroyed_ = true;
   }
   if (!lost_context_callback_.is_null())
     base::ResetAndReturn(&lost_context_callback_).Run();
   if (gr_context_)
     gr_context_->OnLostContext();
 }
 
 void ContextProviderCommandBuffer::OnMemoryAllocationChanged(
     const gpu::MemoryAllocation& allocation) {
-  DCHECK(context_thread_checker_.CalledOnValidThread());
-
+  // Note: no thread check here as this should not change the thread for which
+  // this context is currently bound. e.g. a worker context might be unbound
+  // and this should not result in it being bound to the current thread.
   if (memory_policy_changed_callback_.is_null())
     return;
 
   memory_policy_changed_callback_.Run(cc::ManagedMemoryPolicy(allocation));
 }
 
 void ContextProviderCommandBuffer::InitializeCapabilities() {
   Capabilities caps;
   caps.gpu = context3d_->GetImplementation()->capabilities();
 
@@ skipping 29 matching lines @@
 
   if (!memory_policy_changed_callback_.is_null()) {
     DCHECK(context3d_->GetCommandBufferProxy());
     context3d_->GetCommandBufferProxy()->SetMemoryAllocationChangedCallback(
         base::Bind(&ContextProviderCommandBuffer::OnMemoryAllocationChanged,
                    base::Unretained(this)));
   }
 }
 
 }  // namespace content