Remove forced commit and readback from the scheduler.

cc/trees/thread_proxy.cc

Index: cc/trees/thread_proxy.cc
diff --git a/cc/trees/thread_proxy.cc b/cc/trees/thread_proxy.cc
index ee7f2ee8f8063d31aeeacfb36c01e80398614575..c43badb205a50a966352d01871c12365863986e5 100644
--- a/cc/trees/thread_proxy.cc
+++ b/cc/trees/thread_proxy.cc
@@ -1152,12 +1152,6 @@ DrawResult ThreadProxy::ScheduledActionDrawAndSwapForced() {
   return DrawSwapInternal(forced_draw);
 }
 
-DrawResult ThreadProxy::ScheduledActionDrawAndReadback() {
-  TRACE_EVENT0("cc", "ThreadProxy::ScheduledActionDrawAndReadback");
-  NOTREACHED();
-  return INVALID_RESULT;
-}
-
 void ThreadProxy::DidAnticipatedDrawTimeChange(base::TimeTicks time) {
   if (impl().current_resource_update_controller)
     impl().current_resource_update_controller->PerformMoreUpdates(time);