Bug 1433856 - Block PluginModuleChromeParent::CleanupFromTimeout from recursing. r=jimm

CleanupFromTimeout is (transitively) recursing in calls to Close(), as that now leads to shutting down the plugin broker thread and CleanupFromTimeout was being rerun since nsThread::Shutdown runs tasks..

dom/plugins/ipc/PluginModuleParent.cpp

@@ -647,6 +647,7 @@ PluginModuleChromeParent::PluginModuleChromeParent(const char* aFilePath,
     , mFlashProcess2(0)
     , mFinishInitTask(nullptr)
 #endif
+    , mIsCleaningFromTimeout(false)
 {
     NS_ASSERTION(mSubprocess, "Out of memory!");
     mSandboxLevel = aSandboxLevel;
@@ -804,6 +805,15 @@ PluginModuleChromeParent::CleanupFromTimeout(const bool aFromHangUI)
         return;
     }
 
+    // Avoid recursively calling this method.  MessageChannel::Close() can
+    // cause this task to be re-launched.
+    if (mIsCleaningFromTimeout) {
+      return;
+    }
+
+    AutoRestore<bool> resetCleaningFlag(mIsCleaningFromTimeout);
+    mIsCleaningFromTimeout = true;
+
     /* If the plugin container was terminated by the Plugin Hang UI,
        then either the I/O thread detects a channel error, or the
        main thread must set the error (whomever gets there first).

dom/plugins/ipc/PluginModuleParent.h

@@ -605,6 +605,8 @@ private:
     TakeFullMinidumpCallback mTakeFullMinidumpCallback;
 
     TerminateChildProcessCallback mTerminateChildProcessCallback;
+
+    bool mIsCleaningFromTimeout;
 };
 
 } // namespace plugins