Revert of cc: SwapAck throttle Swap without throttling MainFrames

cc/scheduler/scheduler_state_machine.cc

Index: cc/scheduler/scheduler_state_machine.cc
diff --git a/cc/scheduler/scheduler_state_machine.cc b/cc/scheduler/scheduler_state_machine.cc
index 7cf4bb60a3646c706ad57d67acc0c255f27b17e0..02448897daf82ec3fa5ddde25622eeaeb2217d6d 100644
--- a/cc/scheduler/scheduler_state_machine.cc
+++ b/cc/scheduler/scheduler_state_machine.cc
@@ -480,6 +480,11 @@
   if (!HasInitializedOutputSurface())
     return false;
 
+  // SwapAck throttle the BeginMainFrames
+  // TODO(brianderson): Remove this restriction to improve throughput.
+  if (pending_swaps_ >= max_pending_swaps_)
+    return false;
+
   if (skip_begin_main_frame_to_reduce_latency_)
     return false;