Bug 832665 - Switching back and forth between the music app and FM radio (using home key) causes some unexpected behavior., r=mchen

dom/audiochannel/AudioChannelService.cpp

@@ -67,6 +67,7 @@ NS_IMPL_ISUPPORTS0(AudioChannelService)
 
 AudioChannelService::AudioChannelService()
 : mCurrentHigherChannel(AUDIO_CHANNEL_LAST)
+, mActiveContentChildIDsFrozen(false)
 {
   // Creation of the hash table.
   mAgents.Init();
@@ -169,6 +170,27 @@ AudioChannelService::GetMutedInternal(AudioChannelType aType, uint64_t aChildID,
     mChannelCounters[oldType].RemoveElement(aChildID);
   }
 
+  // If the audio content channel is visible, let's remember this ChildID.
+  if (newType == AUDIO_CHANNEL_INT_CONTENT &&
+      oldType == AUDIO_CHANNEL_INT_CONTENT_HIDDEN &&
+      !mActiveContentChildIDs.Contains(aChildID)) {
+
+    if (mActiveContentChildIDsFrozen) {
+      mActiveContentChildIDsFrozen = false;
+      mActiveContentChildIDs.Clear();
+    }
+
+    mActiveContentChildIDs.AppendElement(aChildID);
+  }
+
+  // If nothing is visible, the list has to been frozen.
+  else if (newType == AUDIO_CHANNEL_INT_CONTENT_HIDDEN &&
+           oldType == AUDIO_CHANNEL_INT_CONTENT &&
+           !mActiveContentChildIDsFrozen &&
+           mChannelCounters[AUDIO_CHANNEL_INT_CONTENT].IsEmpty()) {
+    mActiveContentChildIDsFrozen = true;
+  }
+
   // Let play any visible audio channel.
   if (!aElementHidden) {
     return false;
@@ -179,8 +201,7 @@ AudioChannelService::GetMutedInternal(AudioChannelType aType, uint64_t aChildID,
   // We are not visible, maybe we have to mute.
   if (newType == AUDIO_CHANNEL_INT_NORMAL_HIDDEN ||
       (newType == AUDIO_CHANNEL_INT_CONTENT_HIDDEN &&
-       (!mChannelCounters[AUDIO_CHANNEL_INT_CONTENT].IsEmpty() ||
-        HasMoreThanOneContentChannelHidden()))) {
+       !mActiveContentChildIDs.Contains(aChildID))) {
     muted = true;
   }
 
@@ -199,25 +220,6 @@ AudioChannelService::ContentChannelIsActive()
          !mChannelCounters[AUDIO_CHANNEL_INT_CONTENT_HIDDEN].IsEmpty();
 }
 
-bool
-AudioChannelService::HasMoreThanOneContentChannelHidden()
-{
-  uint32_t childId = CONTENT_PARENT_UNKNOWN_CHILD_ID;
-  bool empty = true;
-  for (uint32_t i = 0;
-       i < mChannelCounters[AUDIO_CHANNEL_INT_CONTENT_HIDDEN].Length();
-       ++i) {
-    if (empty) {
-      childId = mChannelCounters[AUDIO_CHANNEL_INT_CONTENT_HIDDEN][i];
-      empty = false;
-    } else if (childId != mChannelCounters[AUDIO_CHANNEL_INT_CONTENT_HIDDEN][i]) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
 void
 AudioChannelService::SendAudioChannelChangedNotification()
 {
@@ -279,8 +281,7 @@ AudioChannelService::SendAudioChannelChangedNotification()
   }
 
   // Content channels play in background if just one is active.
-  else if ((!mChannelCounters[AUDIO_CHANNEL_INT_CONTENT_HIDDEN].IsEmpty() &&
-            !HasMoreThanOneContentChannelHidden())) {
+  else if (!mActiveContentChildIDs.IsEmpty()) {
     higher = AUDIO_CHANNEL_CONTENT;
   }
 
@@ -391,6 +392,10 @@ AudioChannelService::Observe(nsISupports* aSubject, const char* aTopic, const PR
       while ((index = mChannelCounters[type].IndexOf(childID)) != -1) {
         mChannelCounters[type].RemoveElementAt(index);
       }
+
+      if ((index = mActiveContentChildIDs.IndexOf(childID)) != -1) {
+        mActiveContentChildIDs.RemoveElementAt(index);
+      }
     }
 
     // We don't have to remove the agents from the mAgents hashtable because if

dom/audiochannel/AudioChannelService.h

@@ -98,8 +98,6 @@ protected:
 
   bool ChannelsActiveWithHigherPriorityThan(AudioChannelInternalType aType);
 
-  bool HasMoreThanOneContentChannelHidden();
-
   const char* ChannelName(AudioChannelType aType);
 
   AudioChannelInternalType GetInternalType(AudioChannelType aType,
@@ -130,6 +128,9 @@ protected:
 
   AudioChannelType mCurrentHigherChannel;
 
+  nsTArray<uint64_t> mActiveContentChildIDs;
+  bool mActiveContentChildIDsFrozen;
+
   // This is needed for IPC comunication between
   // AudioChannelServiceChild and this class.
   friend class ContentParent;

dom/audiochannel/tests/TestAudioChannelService.cpp

@@ -145,6 +145,12 @@ TestContentChannels()
   rv = agent2.Init();
   NS_ENSURE_SUCCESS(rv, rv);
 
+  rv = agent1.mAgent->SetVisibilityState(true);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  rv = agent2.mAgent->SetVisibilityState(true);
+  NS_ENSURE_SUCCESS(rv, rv);
+
   bool playing;
   rv = agent1.StartPlaying(&playing);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -166,7 +172,7 @@ TestContentChannels()
 
   rv = agent2.StartPlaying(&playing);
   NS_ENSURE_SUCCESS(rv, rv);
-  TEST_ENSURE_BASE(!playing, "Test3: A content channel unvisible agent2 should not be playing");
+  TEST_ENSURE_BASE(playing, "Test3: A content channel unvisible agent2 should be playing");
 
   rv = agent1.mAgent->SetVisibilityState(true);
   NS_ENSURE_SUCCESS(rv, rv);