[chrome.displaySource] Use a scoped enumeration for initialization steps.

extensions/renderer/api/display_source/wifi_display/wifi_display_media_pipeline.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 "extensions/renderer/api/display_source/wifi_display/wifi_display_media_pipeline.h"
 
 #include "base/logging.h"
 #include "content/public/renderer/render_thread.h"
 #include "content/public/renderer/video_encode_accelerator.h"
 
@@ skipping 52 matching lines @@
     base::TimeTicks reference_time) {
   DCHECK(video_encoder_);
   video_encoder_->InsertRawVideoFrame(video_frame, reference_time);
 }
 
 void WiFiDisplayMediaPipeline::RequestIDRPicture() {
   DCHECK(video_encoder_);
   video_encoder_->RequestIDRPicture();
 }
 
-enum WiFiDisplayMediaPipeline::InitializationStep : unsigned {
-  INITIALIZE_FIRST,
-  INITIALIZE_AUDIO_ENCODER = INITIALIZE_FIRST,
-  INITIALIZE_VIDEO_ENCODER,
-  INITIALIZE_MEDIA_PACKETIZER,
-  INITIALIZE_MEDIA_SERVICE,
-  INITIALIZE_LAST = INITIALIZE_MEDIA_SERVICE
+enum class WiFiDisplayMediaPipeline::InitializationStep : unsigned {
+  FIRST,
+  AUDIO_ENCODER = FIRST,
+  VIDEO_ENCODER,
+  MEDIA_PACKETIZER,
+  MEDIA_SERVICE,
+  LAST = MEDIA_SERVICE
 };
 
 void WiFiDisplayMediaPipeline::Initialize(
     const InitCompletionCallback& callback) {
   DCHECK(!audio_encoder_ && !video_encoder_ && !packetizer_);
-  OnInitialize(callback, INITIALIZE_FIRST, true);
+  OnInitialize(callback, InitializationStep::FIRST, true);
 }
 
 void WiFiDisplayMediaPipeline::OnInitialize(
     const InitCompletionCallback& callback,
     InitializationStep current_step,
     bool success) {
   if (!success) {
     callback.Run(false);
     return;
   }
 
   InitStepCompletionCallback init_step_callback;
-  if (current_step < INITIALIZE_LAST) {
-    InitializationStep next_step =
-        static_cast<InitializationStep>(current_step + 1u);
-    init_step_callback = base::Bind(&WiFiDisplayMediaPipeline::OnInitialize,
-                               weak_factory_.GetWeakPtr(), callback, next_step);
+  if (current_step < InitializationStep::LAST) {
+    InitializationStep next_step = static_cast<InitializationStep>(
+        static_cast<unsigned>(current_step) + 1u);
+    init_step_callback =
+        base::Bind(&WiFiDisplayMediaPipeline::OnInitialize,
+                   weak_factory_.GetWeakPtr(), callback, next_step);
   }
 
   switch (current_step) {
-    case INITIALIZE_AUDIO_ENCODER:
+    case InitializationStep::AUDIO_ENCODER:
       DCHECK(!audio_encoder_);
       if (type_ & wds::AudioSession) {
         auto result_callback =
             base::Bind(&WiFiDisplayMediaPipeline::OnAudioEncoderCreated,
                        weak_factory_.GetWeakPtr(), init_step_callback);
         WiFiDisplayAudioEncoder::Create(audio_codec_, result_callback);
       } else {
         init_step_callback.Run(true);
       }
       break;
-    case INITIALIZE_VIDEO_ENCODER:
+    case InitializationStep::VIDEO_ENCODER:
       DCHECK(!video_encoder_);
       if (type_ & wds::VideoSession) {
         auto result_callback =
             base::Bind(&WiFiDisplayMediaPipeline::OnVideoEncoderCreated,
                        weak_factory_.GetWeakPtr(), init_step_callback);
         WiFiDisplayVideoEncoder::Create(video_parameters_, result_callback);
       } else {
         init_step_callback.Run(true);
       }
       break;
-    case INITIALIZE_MEDIA_PACKETIZER:
+    case InitializationStep::MEDIA_PACKETIZER:
       DCHECK(!packetizer_);
       CreateMediaPacketizer();
       init_step_callback.Run(true);
       break;
-    case INITIALIZE_MEDIA_SERVICE:
+    case InitializationStep::MEDIA_SERVICE:
       service_callback_.Run(
           mojo::GetProxy(&media_service_),
           base::Bind(&WiFiDisplayMediaPipeline::OnMediaServiceRegistered,
                      weak_factory_.GetWeakPtr(), callback));
       break;
   }
 }
 
 void WiFiDisplayMediaPipeline::CreateMediaPacketizer() {
   DCHECK(!packetizer_);
@@ skipping 88 matching lines @@
 }
 
 bool WiFiDisplayMediaPipeline::OnPacketizedMediaDatagramPacket(
     WiFiDisplayMediaDatagramPacket media_datagram_packet) {
   DCHECK(media_service_);
   media_service_->SendMediaPacket(std::move(media_datagram_packet));
   return true;
 }
 
 }  // namespace extensions