Update from chromium https://crrev.com/302282

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 31b9b272013989ced09e369921056b3d988da66b..45f36e27816d04451e1f92e786dcf21911fd3f34 100644
--- a/cc/resources/resource_pool.cc
+++ b/cc/resources/resource_pool.cc
@@ -105,12 +105,15 @@ bool ResourcePool::ResourceUsageTooHigh() {
   return false;
 }
 
-void ResourcePool::CheckBusyResources() {
+void ResourcePool::CheckBusyResources(bool wait_if_needed) {
   ResourceList::iterator it = busy_resources_.begin();
 
   while (it != busy_resources_.end()) {
     ScopedResource* resource = *it;
 
+    if (wait_if_needed)
+      resource_provider_->WaitReadLockIfNeeded(resource->id());
+
     if (resource_provider_->CanLockForWrite(resource->id())) {
       DidFinishUsingResource(resource);
       it = busy_resources_.erase(it);