Mac: Suppress asserts about resources being in use

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 54411aa1853e3ffbec18d1ce93cb664b444e2d0d..898bc81c102abbcb1b73fd72e1ab06a2b3350a42 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -787,8 +787,10 @@ void ResourceProvider::UnlockForRead(ResourceId id) {
 
 ResourceProvider::Resource* ResourceProvider::LockForWrite(ResourceId id) {
   Resource* resource = GetResource(id);
-  DCHECK(CanLockForWrite(id));
-
+  // TODO(ccameron): The allowance for IsInUseByMacOSWindowServer should not
+  // be needed.
+  // http://crbug.com/577121
+  DCHECK(CanLockForWrite(id) || IsInUseByMacOSWindowServer(id));
   resource->locked_for_write = true;
   return resource;
 }
@@ -807,6 +809,12 @@ bool ResourceProvider::IsOverlayCandidate(ResourceId id) {
   return resource->is_overlay_candidate;
 }
 
+bool ResourceProvider::IsInUseByMacOSWindowServer(ResourceId id) {
+  Resource* resource = GetResource(id);
+  return resource->gpu_memory_buffer &&
+         resource->gpu_memory_buffer->IsInUseByMacOSWindowServer();
+}
+
 void ResourceProvider::UnlockForWrite(ResourceProvider::Resource* resource) {
   DCHECK(resource->locked_for_write);
   DCHECK_EQ(resource->exported_count, 0);