cc: Use gpu raster in HUD.

cc/output/context_provider.h

Index: cc/output/context_provider.h
diff --git a/cc/output/context_provider.h b/cc/output/context_provider.h
index 44c69412d3ba901268b3a60c96203e2c5755a0e7..c993a1172d7264bdc32dcb85bad0784e67705dec 100644
--- a/cc/output/context_provider.h
+++ b/cc/output/context_provider.h
@@ -50,6 +50,19 @@ class ContextProvider : public base::RefCountedThreadSafe<ContextProvider> {
     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