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

cc/resources/resource_pool.cc

Index: cc/resources/resource_pool.cc
diff --git a/cc/resources/resource_pool.cc b/cc/resources/resource_pool.cc
index 8bba2cbf18577570fe293e3c7509db46c42615f9..5a6654e001ba687af6621f37933e8c70a496a9d8 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -205,14 +205,11 @@ void ResourcePool::DeleteResource(scoped_ptr<PoolResource> resource) {
   --resource_count_;
 }
 
-void ResourcePool::CheckBusyResources(bool wait_if_needed) {
+void ResourcePool::CheckBusyResources() {
   for (size_t i = 0; i < busy_resources_.size();) {
     ResourceDeque::iterator it(busy_resources_.begin() + i);
     PoolResource* resource = *it;
 
-    if (wait_if_needed)
-      resource_provider_->WaitReadLockIfNeeded(resource->id());
-
     if (resource_provider_->CanLockForWrite(resource->id())) {
       DidFinishUsingResource(busy_resources_.take(it));
     } else if (resource_provider_->IsLost(resource->id())) {