cc: Use gpu raster in HUD.

cc/output/context_provider.h

 // 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.
 
 #ifndef CC_OUTPUT_CONTEXT_PROVIDER_H_
 #define CC_OUTPUT_CONTEXT_PROVIDER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 32 matching lines @@
     gpu::gles2::GLES2Interface* ContextGL() {
       return context_provider_->ContextGL();
     }
 
    private:
     ContextProvider* const context_provider_;
     base::AutoLock context_lock_;
     std::unique_ptr<ContextCacheController::ScopedBusy> busy_;
   };
 
+  class CC_EXPORT ScopedContext {

[danakj, 2017/05/01 22:57:33]

I don't think this class is doing more than if you just hold a
ContextCacheController::ScopedBusy directly, since all it does is return the
context provider you passed in. So I think I'd prefer just doing that.

Using an RAII object is helpful to make sure something is done, but in this case
the ScopedBusy already is one, and will complain if not handed back to the
context provider.

[sohan, 2017/05/03 11:06:35]

Done.

+   public:
+    explicit ScopedContext(ContextProvider* context_provider);
+    ~ScopedContext();
+
+    gpu::gles2::GLES2Interface* ContextGL() {
+      return context_provider_->ContextGL();
+    }
+
+   private:
+    ContextProvider* const context_provider_;
+    std::unique_ptr<ContextCacheController::ScopedBusy> busy_;
+  };
   // Bind the 3d context to the current thread. This should be called before
   // accessing the contexts. Calling it more than once should have no effect.
   // Once this function has been called, the class should only be accessed
   // from the same thread unless the function has some explicitly specified
   // rules for access on a different thread. See SetupLockOnMainThread(), which
   // can be used to provide access from multiple threads.
   virtual bool BindToCurrentThread() = 0;
 
   virtual gpu::gles2::GLES2Interface* ContextGL() = 0;
   virtual gpu::ContextSupport* ContextSupport() = 0;
@@ skipping 29 matching lines @@
   virtual base::Lock* GetLock() = 0;
 
  protected:
   friend class base::RefCountedThreadSafe<ContextProvider>;
   virtual ~ContextProvider() {}
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_CONTEXT_PROVIDER_H_