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 f5c71678f2740a5966f41958c08a0bf49f77ae70..f60eba80c9aa0d7c4e2fdc9bbccc057ff161766f 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -131,15 +131,12 @@ bool ResourcePool::ResourceUsageTooHigh() {
   return false;
 }
 
-void ResourcePool::CheckBusyResources(bool wait_if_needed) {
+void ResourcePool::CheckBusyResources() {
   ResourceList::iterator it = busy_resources_.begin();
 
   while (it != busy_resources_.end()) {
     ScopedResource* resource = it->resource;
 
-    if (wait_if_needed)
-      resource_provider_->WaitReadLockIfNeeded(resource->id());
-
     if (resource_provider_->CanLockForWrite(resource->id())) {
       DidFinishUsingResource(resource, it->content_id);
       it = busy_resources_.erase(it);