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 7b65d344ab367fb24ecdb5217738954024df8cef..7ef91beb4f3767f6a873ddcff832a5b80d4e310e 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -136,15 +136,12 @@ void ResourcePool::DeleteResource(ScopedResource* resource) {
   delete resource;
 }
 
-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);