Make AudioContentType/VolumeChangeSource easier to print

No need to add XXXToString helper function in each file.

Bug: None
Change-Id: Ie717defac4f4444aeab207de472ae190f935ac1e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2220359
Commit-Queue: Linkun Chen <lkchen@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#778526}

chromecast/common/BUILD.gn

@@ -26,6 +26,15 @@ cast_source_set("resource_delegate") {
   ]
 }
 
+cast_source_set("volume_control_enum_printer") {
+  sources = [ "volume_control_enum_printer.cc" ]
+
+  deps = [
+    "//base",
+    "//chromecast/public",
+  ]
+}
+
 cast_source_set("activity_url_filter") {
   sources = [
     "activity_filtering_url_loader_throttle.cc",

chromecast/common/volume_control_enum_printer.cc

@@ -0,0 +1,41 @@
+// Copyright 2020 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 "chromecast/public/volume_control.h"
+
+#include "base/notreached.h"
+
+namespace chromecast {
+namespace media {
+
+std::ostream& operator<<(std::ostream& os, AudioContentType audio_type) {
+  switch (audio_type) {
+    case AudioContentType::kMedia:
+      return os << "MEDIA";
+    case AudioContentType::kAlarm:
+      return os << "ALARM";
+    case AudioContentType::kCommunication:
+      return os << "COMMUNICATION";
+    case AudioContentType::kOther:
+      return os << "OTHER";
+    default:
+      NOTREACHED()
+          << "Add a new entry above, otherwise kNumTypes is not a valid type.";
+      return os << "UNKNOWN";
+  }
+}
+
+std::ostream& operator<<(std::ostream& os,
+                         VolumeChangeSource vol_change_source) {
+  switch (vol_change_source) {
+    case VolumeChangeSource::kUser:
+      return os << "USER";
+    case VolumeChangeSource::kAutomatic:
+      return os << "AUTOMATIC";
+    case VolumeChangeSource::kAutoWithFeedback:
+      return os << "AUTO_WITH_FEEDBACK";
+  }
+}
+
+}  // namespace media
+}  // namespace chromecast

chromecast/media/BUILD.gn

@@ -76,6 +76,7 @@ test("cast_media_unittests") {
     "//chromecast:chromecast_buildflags",
     "//chromecast/base",
     "//chromecast/base/metrics:test_support",
+    "//chromecast/common:volume_control_enum_printer",
     "//chromecast/common/mojom",
     "//chromecast/media/api:test_support",
     "//chromecast/media/audio:unittests",

chromecast/media/cma/backend/mixer/BUILD.gn

@@ -71,6 +71,7 @@ cast_source_set("mixer") {
     "//chromecast/base",
     "//chromecast/base:chromecast_switches",
     "//chromecast/base:thread_health_checker",
+    "//chromecast/common:volume_control_enum_printer",
     "//chromecast/media/audio:audio_io_thread",
     "//chromecast/media/audio:interleaved_channel_mixer",
     "//chromecast/media/audio:libcast_external_audio_pipeline_1.0",

chromecast/media/cma/backend/mixer/stream_mixer.cc

@@ -908,8 +908,7 @@ void StreamMixer::SetOutputLimit(AudioContentType type, float limit) {
   MAKE_SURE_MIXER_THREAD(SetOutputLimit, type, limit);
   DCHECK(type != AudioContentType::kOther);
 
-  LOG(INFO) << "Set volume limit for " << static_cast<int>(type) << " to "
-            << limit;
+  LOG(INFO) << "Set volume limit for " << type << " to " << limit;
   volume_info_[type].limit = limit;
   int fade_ms = kUseDefaultFade;
   if (type == AudioContentType::kMedia) {

chromecast/public/volume_control.h

@@ -5,6 +5,7 @@
 #ifndef CHROMECAST_PUBLIC_VOLUME_CONTROL_H_
 #define CHROMECAST_PUBLIC_VOLUME_CONTROL_H_
 
+#include <ostream>
 #include <string>
 #include <vector>
 
@@ -24,6 +25,10 @@ enum class AudioContentType {
   kNumTypes,       // Not a valid type; should always be last in the enum.
 };
 
+// In case of link issue, implement it by your own or depend on
+// c/common/volume_control_enum_printer
+std::ostream& operator<<(std::ostream& os, AudioContentType audio_type);
+
 // Different sources of volume changes. Used to change behaviour (eg feedback
 // sounds) based on the source.
 enum class VolumeChangeSource {
@@ -33,6 +38,11 @@ enum class VolumeChangeSource {
                       // volume feedback UX.
 };
 
+// In case of link issue, implement it by your own or depend on
+// c/common/volume_control_enum_printer
+std::ostream& operator<<(std::ostream& os,
+                         VolumeChangeSource vol_change_source);
+
 // Observer for volume/mute state changes. This is useful to detect volume
 // changes that occur outside of cast_shell. Add/RemoveVolumeObserver() must not
 // be called synchronously from OnVolumeChange() or OnMuteChange(). Note that