cc: Free gpu resources when we are invisible or TM is oom.

cc/resources/resource_provider.cc

 // Copyright 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 "cc/resources/resource_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/containers/hash_tables.h"
@@ skipping 2133 matching lines @@
   return context_provider ? context_provider->ContextGL() : NULL;
 }
 
 class GrContext* ResourceProvider::GrContext(bool worker_context) const {
   ContextProvider* context_provider =
       worker_context ? output_surface_->worker_context_provider()
                      : output_surface_->context_provider();
   return context_provider ? context_provider->GrContext() : NULL;
 }
 
+void ResourceProvider::FreeGrResources() {
+  if (!output_surface_)
+    return;
+
+  ContextProvider* context_provider =
+      output_surface_->worker_context_provider();
+  if (!context_provider)
+    return;
+
+  // The context lock must be held while accessing the context on a
+  // worker thread.
+  base::AutoLock context_lock(*context_provider->GetLock());
+
+  // Allow context to bind to current thread.
+  context_provider->DetachFromThread();
+
+  class GrContext* gr_context = context_provider->GrContext();
+  DCHECK(gr_context);
+  gr_context->freeGpuResources();
+
+  // Allow context to bind to other threads.
+  context_provider->DetachFromThread();
+}
+
 }  // namespace cc