cc: Implement shared worker contexts. (v1)

content/common/gpu/client/context_provider_command_buffer.cc

Index: content/common/gpu/client/context_provider_command_buffer.cc
diff --git a/content/common/gpu/client/context_provider_command_buffer.cc b/content/common/gpu/client/context_provider_command_buffer.cc
index ba9f0ebfbed6a6f75196c29a7bf89da933557773..5379e5bd6044aaedb530a44c9a215e68379ec1f5 100644
--- a/content/common/gpu/client/context_provider_command_buffer.cc
+++ b/content/common/gpu/client/context_provider_command_buffer.cc
@@ -109,6 +109,12 @@ bool ContextProviderCommandBuffer::BindToCurrentThread() {
 }
 
 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();
 }
 
@@ -182,7 +188,9 @@ void ContextProviderCommandBuffer::DeleteCachedResources() {
 }
 
 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_)
@@ -197,8 +205,9 @@ void ContextProviderCommandBuffer::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;