Bug 1317670 Part 1 - r=jib

dom/media/MediaManager.cpp

@@ -2696,6 +2696,7 @@ MediaManager::OnNavigation(uint64_t aWindowID)
 void
 MediaManager::RemoveMediaDevicesCallback(uint64_t aWindowID)
 {
+  MutexAutoLock lock(mCallbackMutex);
   for (DeviceChangeCallback* observer : mDeviceChangeCallbackList)
   {
     dom::MediaDevices* mediadevices = static_cast<dom::MediaDevices *>(observer);
@@ -2704,7 +2705,7 @@ MediaManager::RemoveMediaDevicesCallback(uint64_t aWindowID)
       nsPIDOMWindowInner* window = mediadevices->GetOwner();
       MOZ_ASSERT(window);
       if (window && window->WindowID() == aWindowID) {
-        DeviceChangeCallback::RemoveDeviceChangeCallback(observer);
+        DeviceChangeCallback::RemoveDeviceChangeCallbackLocked(observer);
         return;
       }
     }

dom/media/systemservices/DeviceChangeCallback.h

@@ -32,6 +32,12 @@ public:
   virtual int RemoveDeviceChangeCallback(DeviceChangeCallback* aCallback)
   {
     MutexAutoLock lock(mCallbackMutex);
+    return RemoveDeviceChangeCallbackLocked(aCallback);
+  }
+
+  virtual int RemoveDeviceChangeCallbackLocked(DeviceChangeCallback* aCallback)
+  {
+    mCallbackMutex.AssertCurrentThreadOwns();
     if (mDeviceChangeCallbackList.IndexOf(aCallback) != mDeviceChangeCallbackList.NoIndex)
       mDeviceChangeCallbackList.RemoveElement(aCallback);
     return 0;
@@ -39,12 +45,10 @@ public:
 
   DeviceChangeCallback() : mCallbackMutex("mozilla::media::DeviceChangeCallback::mCallbackMutex")
   {
-    mDeviceChangeCallbackList.Clear();
   }
 
   virtual ~DeviceChangeCallback()
   {
-    mDeviceChangeCallbackList.Clear();
   }
 
 protected: