(not for commit) Create 2nd ContextProvider for Ganesh rasterization.

cc/output/output_surface.h

Index: cc/output/output_surface.h
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 29e32a5317ef3c61f2b329f6a390d1eb0d0f115f..19ee75b0c8933eb9cb48f87df9c088ecb3791928 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -15,6 +15,7 @@
 #include "cc/output/context_provider.h"
 #include "cc/output/overlay_candidate_validator.h"
 #include "cc/output/software_output_device.h"
+#include "cc/resources/scoped_gpu_raster.h"
 
 namespace base { class SingleThreadTaskRunner; }
 
@@ -49,9 +50,13 @@ class CC_EXPORT OutputSurface {
   explicit OutputSurface(
       const scoped_refptr<ContextProvider>& context_provider);
 
+  OutputSurface(const scoped_refptr<ContextProvider>& context_provider,
+                const scoped_refptr<ContextProvider>& worker_context_provider);
+
   explicit OutputSurface(scoped_ptr<SoftwareOutputDevice> software_device);
 
   OutputSurface(const scoped_refptr<ContextProvider>& context_provider,
+                const scoped_refptr<ContextProvider>& worker_context_provider,
                 scoped_ptr<SoftwareOutputDevice> software_device);
 
   virtual ~OutputSurface();
@@ -94,6 +99,9 @@ class CC_EXPORT OutputSurface {
   // In the event of a lost context, the entire output surface should be
   // recreated.
   ContextProvider* context_provider() const { return context_provider_.get(); }
+  ContextProvider* worker_context_provider() const {
+    return worker_context_provider_.get();
+  }
   SoftwareOutputDevice* software_device() const {
     return software_device_.get();
   }
@@ -156,6 +164,7 @@ class CC_EXPORT OutputSurface {
 
   struct OutputSurface::Capabilities capabilities_;
   scoped_refptr<ContextProvider> context_provider_;
+  scoped_refptr<ContextProvider> worker_context_provider_;
   scoped_ptr<SoftwareOutputDevice> software_device_;
   scoped_ptr<OverlayCandidateValidator> overlay_candidate_validator_;
   gfx::Size surface_size_;