AudioManager: isFixedVolume() fix for dynamic volume behavior

AudioManager.isFixedVolume() was only considering the fixed volume
global property, but was not checking the current volume behavior.

Bug: 203034282
Test: atest MediaActivityTest ; atest MediaRouter2Test#testCallbacksAreCalledWhenVolumeChanged
Change-Id: I1e22e5bcd75c41c1ab6a47dc1e0d7619df989970

media/java/android/media/AudioManager.java

@@ -96,8 +96,6 @@ public class AudioManager {
     private Context mOriginalContext;
     private Context mApplicationContext;
     private long mVolumeKeyUpTime;
-    private boolean mUseFixedVolumeInitialized;
-    private boolean mUseFixedVolume;
     private static final String TAG = "AudioManager";
     private static final boolean DEBUG = false;
     private static final AudioPortEventHandler sAudioPortEventHandler = new AudioPortEventHandler();
@@ -893,19 +891,13 @@ public class AudioManager {
      * </ul>
      */
     public boolean isVolumeFixed() {
-        synchronized (this) {
-            try {
-                if (!mUseFixedVolumeInitialized) {
-                    mUseFixedVolume = getContext().getResources().getBoolean(
-                            com.android.internal.R.bool.config_useFixedVolume);
-                }
-            } catch (Exception e) {
-            } finally {
-                // only ever try once, so always consider initialized even if query failed
-                mUseFixedVolumeInitialized = true;
-            }
+        boolean res = false;
+        try {
+            res = getService().isVolumeFixed();
+        } catch (RemoteException e) {
+            Log.e(TAG, "Error querying isVolumeFixed", e);
         }
-        return mUseFixedVolume;
+        return res;
     }
 
     /**

media/java/android/media/IAudioService.aidl

@@ -456,4 +456,6 @@ interface IAudioService {
     void registerSpatializerOutputCallback(in ISpatializerOutputCallback cb);
 
     void unregisterSpatializerOutputCallback(in ISpatializerOutputCallback cb);
+
+    boolean isVolumeFixed();
 }

services/core/java/com/android/server/audio/AudioService.java

@@ -6185,9 +6185,15 @@ public class AudioService extends IAudioService.Stub
      */
     public @AudioManager.DeviceVolumeBehavior
     int getDeviceVolumeBehavior(@NonNull AudioDeviceAttributes device) {
+        Objects.requireNonNull(device);
         // verify permissions
         enforceQueryStateOrModifyRoutingPermission();
 
+        return getDeviceVolumeBehaviorInt(device);
+    }
+
+    private @AudioManager.DeviceVolumeBehavior
+            int getDeviceVolumeBehaviorInt(@NonNull AudioDeviceAttributes device) {
         // translate Java device type to native device type (for the devices masks for full / fixed)
         final int audioSystemDeviceOut = AudioDeviceInfo.convertDeviceTypeToInternalDevice(
                 device.getType());
@@ -6215,6 +6221,29 @@ public class AudioService extends IAudioService.Stub
         return AudioManager.DEVICE_VOLUME_BEHAVIOR_VARIABLE;
     }
 
+    /**
+     * @see AudioManager#isVolumeFixed()
+     * Note there are no permission checks on this operation, as this is part of API 21
+     * @return true if the current device's volume behavior for media is
+     *         DEVICE_VOLUME_BEHAVIOR_FIXED
+     */
+    public boolean isVolumeFixed() {
+        if (mUseFixedVolume) {
+            return true;
+        }
+        final AudioAttributes attributes = new AudioAttributes.Builder()
+                .setUsage(AudioAttributes.USAGE_MEDIA)
+                .build();
+        // calling getDevice*Int to bypass permission check
+        final List<AudioDeviceAttributes> devices = getDevicesForAttributesInt(attributes);
+        for (AudioDeviceAttributes device : devices) {
+            if (getDeviceVolumeBehaviorInt(device) == AudioManager.DEVICE_VOLUME_BEHAVIOR_FIXED) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     /*package*/ static final int CONNECTION_STATE_DISCONNECTED = 0;
     /*package*/ static final int CONNECTION_STATE_CONNECTED = 1;
     /**