cc: Add threaded GPU rasterization.

cc/test/test_context_provider.h

Index: cc/test/test_context_provider.h
diff --git a/cc/test/test_context_provider.h b/cc/test/test_context_provider.h
index 3be8b4365b6278e15ecb413ef6660f4b459058ce..9001f7ee9cbead47a4db52d51605c4bd466a99d0 100644
--- a/cc/test/test_context_provider.h
+++ b/cc/test/test_context_provider.h
@@ -14,6 +14,7 @@
 #include "cc/test/test_context_support.h"
 #include "gpu/command_buffer/client/gles2_interface_stub.h"
 #include "skia/ext/refptr.h"
+#include "third_party/skia/include/gpu/gl/SkGLContext.h"
 
 namespace cc {
 class TestWebGraphicsContext3D;
@@ -29,6 +30,7 @@ class TestContextProvider : public ContextProvider {
       scoped_ptr<TestWebGraphicsContext3D> context);
 
   bool BindToCurrentThread() override;
+  void DetachFromThread() override;
   Capabilities ContextCapabilities() override;
   gpu::gles2::GLES2Interface* ContextGL() override;
   gpu::ContextSupport* ContextSupport() override;
@@ -76,6 +78,7 @@ class TestContextProvider : public ContextProvider {
 
   LostContextCallback lost_context_callback_;
   MemoryPolicyChangedCallback memory_policy_changed_callback_;
+  skia::RefPtr<class SkGLContext> gl_context_;
   skia::RefPtr<class GrContext> gr_context_;
 
   base::WeakPtrFactory<TestContextProvider> weak_ptr_factory_;