Replace "nested message loop" with "nested run loop" in comments.

ui/aura/mus/window_tree_client.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 90 matching lines @@
     if (ack_callback_) {
       ack_callback_->Run(handled_ ? ui::mojom::EventResult::HANDLED
                                   : ui::mojom::EventResult::UNHANDLED);
     }
   }
 
   void set_handled(bool handled) { handled_ = handled; }
 
   // base::RunLoop::NestingObserver:
   void OnBeginNestedRunLoop() override {
-    // Acknowledge the event immediately if a nested message loop starts.
-    // Otherwise we appear unresponsive for the life of the nested message loop.
+    // Acknowledge the event immediately if a nested run loop starts.
+    // Otherwise we appear unresponsive for the life of the nested run loop.
     if (ack_callback_) {
       ack_callback_->Run(ui::mojom::EventResult::HANDLED);
       ack_callback_.reset();
     }
   }
 
  private:
   std::unique_ptr<EventResultCallback> ack_callback_;
   bool handled_ = false;
 
@@ skipping 1915 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura