cc: Implement shared worker contexts. (v1)

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 056879f49d84ba444142101690da109437208d14..894138034d386feb56f4fbadf7bd6d8574364bd7 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -128,12 +128,6 @@ bool OutputSurface::BindToClient(OutputSurfaceClient* client) {
     }
   }
 
-  if (success && worker_context_provider_.get()) {
-    success = worker_context_provider_->BindToCurrentThread();
-    if (success)
-      worker_context_provider_->SetupLock();
-  }
-
   if (!success)
     client_ = NULL;
 
@@ -209,13 +203,15 @@ void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
   if (auto* context_provider = worker_context_provider()) {
     ContextProvider::ScopedContextLock scoped_context(context_provider);
 
-    if (aggressively_free_resources) {
-      context_provider->DeleteCachedResources();
-    }
+    if (!context_provider->HasBeenDestroyed()) {
+      if (aggressively_free_resources) {
+        context_provider->DeleteCachedResources();
+      }
 
-    if (auto* context_support = context_provider->ContextSupport()) {
-      context_support->SetAggressivelyFreeResources(
-          aggressively_free_resources);
+      if (auto* context_support = context_provider->ContextSupport()) {
+        context_support->SetAggressivelyFreeResources(
+            aggressively_free_resources);
+      }
     }
   }
 }