Update bool WindowManager::OnWmSetBounds() to match with its desirable behavior.

services/ui/demo/mus_demo.cc

 // Copyright 2016 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 "services/ui/demo/mus_demo.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/time/time.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "services/service_manager/public/cpp/service_context.h"
@@ skipping 82 matching lines @@
   window_ = nullptr;
   window_tree_client_.reset();
   timer_.Stop();
 }
 
 void MusDemo::OnPointerEventObserved(const PointerEvent& event,
                                      Window* target) {}
 
 void MusDemo::SetWindowManagerClient(WindowManagerClient* client) {}
 
-bool MusDemo::OnWmSetBounds(Window* window, gfx::Rect* bounds) {
-  return true;
-}
+void MusDemo::OnWmSetBounds(Window* window, gfx::Rect* bounds) {}
 
 bool MusDemo::OnWmSetProperty(Window* window,
                               const std::string& name,
                               std::unique_ptr<std::vector<uint8_t>>* new_data) {
   return true;
 }
 
 Window* MusDemo::OnWmCreateTopLevelWindow(
     std::map<std::string, std::vector<uint8_t>>* properties) {
   return nullptr;
@@ skipping 88 matching lines @@
   BitmapUploader::Format bitmap_format = BitmapUploader::BGRA;
 #endif
 
   // Send frame to MUS via BitmapUploader.
   uploader_->SetBitmap(bounds.width(), bounds.height(), std::move(data),
                        bitmap_format);
 }
 
 }  // namespace demo
 }  // namespace ui