Add chromecast flag and check for volume control of single volume

platforms.

Bug: b/111922445
Test: Successfully build CastShell.
Change-Id: Iaf61f099001370fb3b948654e126ffa91f6e57d7
Reviewed-on: https://chromium-review.googlesource.com/1186147
Reviewed-by: Luke Halliwell <halliwell@chromium.org>
Reviewed-by: Kenneth MacKay <kmackay@chromium.org>
Commit-Queue: Melisa Carranza Zúñiga <melisacz@google.com>
Cr-Commit-Position: refs/heads/master@{#585940}

chromecast/BUILD.gn

@@ -583,6 +583,7 @@ buildflag_header("chromecast_buildflags") {
     "ENABLE_CHROMECAST_EXTENSIONS=$enable_chromecast_extensions",
     "ENABLE_CAST_FRAGMENT=$enable_cast_fragment",
     "IS_ANDROID_THINGS_NON_PUBLIC=$is_android_things_non_public",
+    "IS_SINGLE_VOLUME=$is_single_volume",
     "USE_ANDROID_USER_AGENT=$use_android_user_agent",
     "USE_CHROMECAST_CDMS=$use_chromecast_cdms",
   ]

chromecast/chromecast.gni

@@ -46,6 +46,10 @@ declare_args() {
   # Set true for builds targeting Android Things.
   is_android_things = false
 
+  # Set true if the platform works as a single volume device, mapping all
+  # volume streams to a single one.
+  is_single_volume = false
+
   # Set to true to start music apps in headless mode.
   enable_headless_music_mode = false
 

chromecast/media/cma/backend/android/volume_control_android.cc

@@ -189,12 +189,14 @@ void VolumeControlAndroid::InitializeOnThread() {
               << " mute=" << muted_[type];
   }
 
+#if !BUILDFLAG(IS_SINGLE_VOLUME)
   // The kOther content type should not have any type-wide volume control or
   // mute (volume control for kOther is per-stream only). Therefore, ensure
   // that the global volume and mute state fo kOther is initialized correctly
   // (100% volume, and not muted).
   SetVolumeOnThread(AudioContentType::kOther, 1.0f, false /* from_android */);
   SetMutedOnThread(AudioContentType::kOther, false, false /* from_android */);
+#endif
 
   initialize_complete_event_.Signal();
 }
@@ -266,27 +268,31 @@ void VolumeControlAndroid::SetMutedOnThread(AudioContentType type,
 void VolumeControlAndroid::ReportVolumeChangeOnThread(AudioContentType type,
                                                       float level) {
   DCHECK(thread_.task_runner()->BelongsToCurrentThread());
+#if !BUILDFLAG(IS_SINGLE_VOLUME)
   if (type == AudioContentType::kOther) {
     // Volume for AudioContentType::kOther should stay at 1.0.
     Java_VolumeControl_setVolume(base::android::AttachCurrentThread(),
                                  j_volume_control_, static_cast<int>(type),
                                  1.0f);
     return;
   }
+#endif
 
   SetVolumeOnThread(type, level, true /* from android */);
 }
 
 void VolumeControlAndroid::ReportMuteChangeOnThread(AudioContentType type,
                                                     bool muted) {
   DCHECK(thread_.task_runner()->BelongsToCurrentThread());
+#if !BUILDFLAG(IS_SINGLE_VOLUME)
   if (type == AudioContentType::kOther) {
     // Mute state for AudioContentType::kOther should always be false.
     Java_VolumeControl_setMuted(base::android::AttachCurrentThread(),
                                 j_volume_control_, static_cast<int>(type),
                                 false);
     return;
   }
+#endif
 
   SetMutedOnThread(type, muted, true /* from_android */);
 }