Re-land: cc: Use worker context for one-copy tile initialization.

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 a597a87d8456bc65f3ce763d469db9e7e776ed7f..14a328a85b45ec24f912d8fe81513f7e7b4bb9fd 100644
--- a/cc/output/output_surface.cc
+++ b/cc/output/output_surface.cc
@@ -217,11 +217,7 @@ void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
                "OutputSurface::SetWorkerContextShouldAggressivelyFreeResources",
                "aggressively_free_resources", aggressively_free_resources);
   if (auto* context_provider = worker_context_provider()) {
-    // The context lock must be held while accessing the worker context.
-    base::AutoLock context_lock(*context_provider->GetLock());
-
-    // Allow context to bind to current thread.
-    context_provider->DetachFromThread();
+    ContextProvider::ScopedContextGL scoped_context(context_provider);
 
     if (aggressively_free_resources) {
       context_provider->DeleteCachedResources();
@@ -231,9 +227,6 @@ void OutputSurface::SetWorkerContextShouldAggressivelyFreeResources(
       context_support->SetAggressivelyFreeResources(
           aggressively_free_resources);
     }
-
-    // Allow context to bind to other threads.
-    context_provider->DetachFromThread();
   }
 }