[Chromecast] Factor out volume loading

Bug: internal b/163708246
Change-Id: I7868fe3e507af53fa82206652c5dec130efd468c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351390
Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#798018}

chromecast/media/cma/backend/BUILD.gn

@@ -139,6 +139,18 @@ cast_source_set("volume_map") {
   ]
 }
 
+cast_source_set("saved_volumes") {
+  sources = [
+    "saved_volumes.cc",
+    "saved_volumes.h",
+  ]
+  deps = [
+    ":cast_audio_json",
+    "//base",
+    "//chromecast/public",
+  ]
+}
+
 cast_source_set("for_mixer_audio") {
   sources = [
     "audio_decoder_for_mixer.cc",
@@ -152,6 +164,7 @@ cast_source_set("for_mixer_audio") {
     ":audio_buildflags",
     ":cast_audio_json",
     ":public",
+    ":saved_volumes",
     ":volume_map",
     "//base",
     "//chromecast/base",

chromecast/media/cma/backend/saved_volumes.cc

+// 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/media/cma/backend/saved_volumes.h"
+
+#include <string>
+
+#include "base/json/json_file_value_serializer.h"
+#include "base/logging.h"
+#include "base/values.h"
+#include "chromecast/media/cma/backend/cast_audio_json.h"
+
+namespace chromecast {
+namespace media {
+
+namespace {
+
+constexpr float kDefaultMediaDbFS = -25.0f;
+constexpr float kDefaultAlarmDbFS = -20.0f;
+constexpr float kDefaultCommunicationDbFS = -25.0f;
+
+constexpr char kKeyMediaDbFS[] = "dbfs.media";
+constexpr char kKeyAlarmDbFS[] = "dbfs.alarm";
+constexpr char kKeyCommunicationDbFS[] = "dbfs.communication";
+constexpr char kKeyDefaultVolume[] = "default_volume";
+
+std::string ContentTypeToDbFSKey(AudioContentType type) {
+  switch (type) {
+    case AudioContentType::kAlarm:
+      return kKeyAlarmDbFS;
+    case AudioContentType::kCommunication:
+      return kKeyCommunicationDbFS;
+    default:
+      return kKeyMediaDbFS;
+  }
+}
+
+}  // namespace
+
+base::flat_map<AudioContentType, double> LoadSavedVolumes(
+    const base::FilePath& storage_path) {
+  auto types = {AudioContentType::kMedia, AudioContentType::kAlarm,
+                AudioContentType::kCommunication};
+  base::flat_map<AudioContentType, double> volumes;
+
+  volumes[AudioContentType::kMedia] = kDefaultMediaDbFS;
+  volumes[AudioContentType::kAlarm] = kDefaultAlarmDbFS;
+  volumes[AudioContentType::kCommunication] = kDefaultCommunicationDbFS;
+
+  JSONFileValueDeserializer deserializer(storage_path);
+  auto stored_data = deserializer.Deserialize(nullptr, nullptr);
+  if (stored_data && stored_data->is_dict()) {
+    for (auto type : types) {
+      auto v = stored_data->FindDoublePath(ContentTypeToDbFSKey(type));
+      if (v) {
+        volumes[type] = v.value();
+      }
+    }
+    return volumes;
+  }
+
+  LOG(INFO) << "No saved volumes found";
+  // If saved_volumes does not exist, use per-device default if it exists.
+  JSONFileValueDeserializer cast_audio_deserializer(
+      media::CastAudioJson::GetFilePath());
+  auto cast_audio_config = deserializer.Deserialize(nullptr, nullptr);
+  if (!cast_audio_config || !cast_audio_config->is_dict()) {
+    return volumes;
+  }
+
+  const base::Value* default_volume_dict =
+      cast_audio_config->FindDictKey(kKeyDefaultVolume);
+  if (!default_volume_dict) {
+    return volumes;
+  }
+
+  for (auto type : types) {
+    auto v = default_volume_dict->FindDoublePath(ContentTypeToDbFSKey(type));
+    if (v) {
+      LOG(INFO) << "Using default volume for " << ContentTypeToDbFSKey(type)
+                << " of " << v.value();
+      volumes[type] = v.value();
+    }
+  }
+  return volumes;
+}
+
+}  // namespace media
+}  // namespace chromecast

chromecast/media/cma/backend/saved_volumes.h

+// 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.
+
+#ifndef CHROMECAST_MEDIA_CMA_BACKEND_SAVED_VOLUMES_H_
+#define CHROMECAST_MEDIA_CMA_BACKEND_SAVED_VOLUMES_H_
+
+#include "base/containers/flat_map.h"
+#include "base/files/file_path.h"
+#include "chromecast/public/volume_control.h"
+
+namespace chromecast {
+namespace media {
+
+// Returns the saved volume in dBFS for each stream type loaded from persistent
+// storage, or the appropriate default volume if there was no saved volume.
+base::flat_map<AudioContentType, double> LoadSavedVolumes(
+    const base::FilePath& storage_path);
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_BACKEND_SAVED_VOLUMES_H_

chromecast/media/cma/backend/volume_control.cc

@@ -30,7 +30,7 @@
 #include "chromecast/base/serializers.h"
 #include "chromecast/media/audio/mixer_service/control_connection.h"
 #include "chromecast/media/cma/backend/audio_buildflags.h"
-#include "chromecast/media/cma/backend/cast_audio_json.h"
+#include "chromecast/media/cma/backend/saved_volumes.h"
 #include "chromecast/media/cma/backend/system_volume_control.h"
 #include "chromecast/media/cma/backend/volume_map.h"
 
@@ -43,10 +43,6 @@ namespace media {
 
 namespace {
 
-constexpr float kDefaultMediaDbFS = -25.0f;
-constexpr float kDefaultAlarmDbFS = -20.0f;
-constexpr float kDefaultCommunicationDbFS = -25.0f;
-
 #if !BUILDFLAG(SYSTEM_OWNS_VOLUME)
 constexpr float kMinDbFS = -120.0f;
 #endif
@@ -54,7 +50,6 @@ constexpr float kMinDbFS = -120.0f;
 constexpr char kKeyMediaDbFS[] = "dbfs.media";
 constexpr char kKeyAlarmDbFS[] = "dbfs.alarm";
 constexpr char kKeyCommunicationDbFS[] = "dbfs.communication";
-constexpr char kKeyDefaultVolume[] = "default_volume";
 
 #if !BUILDFLAG(SYSTEM_OWNS_VOLUME)
 float DbFsToScale(float db) {
@@ -86,43 +81,12 @@ class VolumeControlInternal : public SystemVolumeControl::Delegate {
     // Load volume map to check that the config file is correct.
     VolumeControl::VolumeToDbFS(0.0f);
 
-    stored_values_.SetDouble(kKeyMediaDbFS, kDefaultMediaDbFS);
-    stored_values_.SetDouble(kKeyAlarmDbFS, kDefaultAlarmDbFS);
-    stored_values_.SetDouble(kKeyCommunicationDbFS, kDefaultCommunicationDbFS);
-
-    auto types = {AudioContentType::kMedia, AudioContentType::kAlarm,
-                  AudioContentType::kCommunication};
-    double volume;
-
     storage_path_ = base::GetHomeDir().Append("saved_volumes");
-    auto old_stored_data = DeserializeJsonFromFile(storage_path_);
-    base::DictionaryValue* old_stored_dict;
-    if (old_stored_data && old_stored_data->GetAsDictionary(&old_stored_dict)) {
-      for (auto type : types) {
-        if (old_stored_dict->GetDouble(ContentTypeToDbFSKey(type), &volume)) {
-          stored_values_.SetDouble(ContentTypeToDbFSKey(type), volume);
-        }
-      }
-    } else {
-      // If saved_volumes does not exist, use per device default if it exists.
-      auto cast_audio_config =
-          DeserializeJsonFromFile(CastAudioJson::GetFilePath());
-      const base::DictionaryValue* cast_audio_dict;
-      if (cast_audio_config &&
-          cast_audio_config->GetAsDictionary(&cast_audio_dict)) {
-        const base::DictionaryValue* default_volume_dict;
-        if (cast_audio_dict && cast_audio_dict->GetDictionary(
-                                   kKeyDefaultVolume, &default_volume_dict)) {
-          for (auto type : types) {
-            if (default_volume_dict->GetDouble(ContentTypeToDbFSKey(type),
-                                               &volume)) {
-              stored_values_.SetDouble(ContentTypeToDbFSKey(type), volume);
-              LOG(INFO) << "Setting default volume for "
-                        << ContentTypeToDbFSKey(type) << " to " << volume;
-            }
-          }
-        }
-      }
+    base::flat_map<AudioContentType, double> saved_volumes =
+        LoadSavedVolumes(storage_path_);
+    for (auto type : {AudioContentType::kMedia, AudioContentType::kAlarm,
+                      AudioContentType::kCommunication}) {
+      stored_values_.SetDouble(ContentTypeToDbFSKey(type), saved_volumes[type]);
     }
 
     base::Thread::Options options;