Bug 1422820 - Don't recurse too much when shutting down cameras. r=pehrsons

--HG--
extra : histedit_source : 2f3145f04e4ca35a412b9870a29ff26d28eab5d6

dom/media/systemservices/CamerasChild.cpp

@@ -34,7 +34,9 @@ CamerasSingleton::CamerasSingleton()
   : mCamerasMutex("CamerasSingleton::mCamerasMutex"),
     mCameras(nullptr),
     mCamerasChildThread(nullptr),
-    mFakeDeviceChangeEventThread(nullptr) {
+    mFakeDeviceChangeEventThread(nullptr),
+    mInShutdown(false)
+{
   LOG(("CamerasSingleton: %p", this));
 }
 
@@ -568,6 +570,9 @@ void
 Shutdown(void)
 {
   OffTheBooksMutexAutoLock lock(CamerasSingleton::Mutex());
+
+  CamerasSingleton::StartShutdown();
+
   CamerasChild* child = CamerasSingleton::Child();
   if (!child) {
     // We don't want to cause everything to get fired up if we're
@@ -728,7 +733,7 @@ CamerasChild::~CamerasChild()
 {
   LOG(("~CamerasChild: %p", this));
 
-  {
+  if (!CamerasSingleton::InShutdown()) {
     OffTheBooksMutexAutoLock lock(CamerasSingleton::Mutex());
     // In normal circumstances we've already shut down and the
     // following does nothing. But on fatal IPC errors we will

dom/media/systemservices/CamerasChild.h

@@ -92,6 +92,14 @@ public:
     return gTheInstance.get()->mFakeDeviceChangeEventThread;
   }
 
+  static bool InShutdown() {
+    return gTheInstance.get()->mInShutdown;
+  }
+
+  static void StartShutdown() {
+    gTheInstance.get()->mInShutdown = true;
+  }
+
 private:
   static Singleton<CamerasSingleton> gTheInstance;
 
@@ -109,6 +117,7 @@ private:
   CamerasChild* mCameras;
   nsCOMPtr<nsIThread> mCamerasChildThread;
   nsCOMPtr<nsIThread> mFakeDeviceChangeEventThread;
+  Atomic<bool> mInShutdown;
 };
 
 // Get a pointer to a CamerasChild object we can use to do IPC with.