Bug 1268559 - Add a safety shutdown timer in ContentChild. r=billm

MozReview-Commit-ID: FVnOvJzErpI

dom/ipc/ContentChild.cpp

@@ -2250,6 +2250,11 @@ ContentChild::RecvSetConnectivity(const bool& connectivity)
 void
 ContentChild::ActorDestroy(ActorDestroyReason why)
 {
+  if (mForceKillTimer) {
+    mForceKillTimer->Cancel();
+    mForceKillTimer = nullptr;
+  }
+
   if (AbnormalShutdown == why) {
     NS_WARNING("shutting down early because of crash!");
     ProcessChild::QuickExit();
@@ -3026,6 +3031,30 @@ ContentChild::RecvDomainSetChanged(const uint32_t& aSetType,
   return true;
 }
 
+void
+ContentChild::StartForceKillTimer()
+{
+  if (mForceKillTimer) {
+    return;
+  }
+
+  int32_t timeoutSecs = Preferences::GetInt("dom.ipc.tabs.shutdownTimeoutSecs", 5);
+  if (timeoutSecs > 0) {
+    mForceKillTimer = do_CreateInstance("@mozilla.org/timer;1");
+    MOZ_ASSERT(mForceKillTimer);
+    mForceKillTimer->InitWithFuncCallback(ContentChild::ForceKillTimerCallback,
+      this,
+      timeoutSecs * 1000,
+      nsITimer::TYPE_ONE_SHOT);
+  }
+}
+
+/* static */ void
+ContentChild::ForceKillTimerCallback(nsITimer* aTimer, void* aClosure)
+{
+  ProcessChild::QuickExit();
+}
+
 bool
 ContentChild::RecvShutdown()
 {
@@ -3055,6 +3084,11 @@ ContentChild::RecvShutdown()
   }
 #endif
 
+  // Start a timer that will insure we quickly exit after a reasonable
+  // period of time. Prevents shutdown hangs after our connection to the
+  // parent closes.
+  StartForceKillTimer();
+
   // Ignore errors here. If this fails, the parent will kill us after a
   // timeout.
   Unused << SendFinishShutdown();

dom/ipc/ContentChild.h

@@ -615,6 +615,9 @@ public:
                           const nsString& aIconPath) override;
 
 private:
+  static void ForceKillTimerCallback(nsITimer* aTimer, void* aClosure);
+  void StartForceKillTimer();
+
   virtual void ActorDestroy(ActorDestroyReason why) override;
 
   virtual void ProcessingError(Result aCode, const char* aReason) override;
@@ -646,6 +649,7 @@ private:
   static ContentChild* sSingleton;
 
   nsCOMPtr<nsIDomainPolicy> mPolicy;
+  nsCOMPtr<nsITimer> mForceKillTimer;
 
   DISALLOW_EVIL_CONSTRUCTORS(ContentChild);
 };