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

ui/compositor/test/in_process_context_provider.cc

Index: ui/compositor/test/in_process_context_provider.cc
diff --git a/ui/compositor/test/in_process_context_provider.cc b/ui/compositor/test/in_process_context_provider.cc
index 76cd19dc191ff8624982205a2d93b573b0058ecb..c5f950f580eacb213905ee6593dc571ea915bff3 100644
--- a/ui/compositor/test/in_process_context_provider.cc
+++ b/ui/compositor/test/in_process_context_provider.cc
@@ -122,10 +122,6 @@
   return true;
 }
 
-void InProcessContextProvider::DetachFromThread() {
-  context_thread_checker_.DetachFromThread();
-}
-
 cc::ContextProvider::Capabilities
 InProcessContextProvider::ContextCapabilities() {
   DCHECK(context_thread_checker_.CalledOnValidThread());