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

cc/output/output_surface.cc

Index: cc/output/output_surface.cc
diff --git a/cc/output/output_surface.cc b/cc/output/output_surface.cc
index b65887e960262262c0f514492f56a49ac0a0e7c3..e5c0713d658277f6d89d0e226f8d25faddd20482 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -21,6 +21,18 @@ OutputSurface::OutputSurface(
     const scoped_refptr<ContextProvider>& context_provider)
     : client_(NULL),
       context_provider_(context_provider),
+      worker_context_provider_(NULL),
+      device_scale_factor_(-1),
+      external_stencil_test_enabled_(false),
+      weak_ptr_factory_(this) {
+}
+
+OutputSurface::OutputSurface(
+    const scoped_refptr<ContextProvider>& context_provider,
+    const scoped_refptr<ContextProvider>& worker_context_provider)
+    : client_(NULL),
+      context_provider_(context_provider),
+      worker_context_provider_(worker_context_provider),
       device_scale_factor_(-1),
       external_stencil_test_enabled_(false),
       weak_ptr_factory_(this) {
@@ -36,9 +48,11 @@ OutputSurface::OutputSurface(scoped_ptr<SoftwareOutputDevice> software_device)
 
 OutputSurface::OutputSurface(
     const scoped_refptr<ContextProvider>& context_provider,
+    const scoped_refptr<ContextProvider>& worker_context_provider,
     scoped_ptr<SoftwareOutputDevice> software_device)
     : client_(NULL),
       context_provider_(context_provider),
+      worker_context_provider_(worker_context_provider),
       software_device_(software_device.Pass()),
       device_scale_factor_(-1),
       external_stencil_test_enabled_(false),
@@ -105,8 +119,14 @@ bool OutputSurface::BindToClient(OutputSurfaceClient* client) {
 
   if (context_provider_.get()) {
     success = context_provider_->BindToCurrentThread();
-    if (success)
+    if (success) {
       SetUpContext3d();
+    }
+  }
+
+  if (worker_context_provider_.get()) {
+    success = worker_context_provider_->BindToCurrentThread();
+    // TODO(vmiura): Callbacks for worker context.
   }
 
   if (!success)