Abort SandboxedUnpacker::RewriteImageFiles on browser shutdown

base/threading/sequenced_worker_pool.h

Index: base/threading/sequenced_worker_pool.h
diff --git a/base/threading/sequenced_worker_pool.h b/base/threading/sequenced_worker_pool.h
index 7e04b071428c838dfcec0faa647f82baf2932045..d21801f0237faabf777319c7eaa624a28ab2f21b 100644
--- a/base/threading/sequenced_worker_pool.h
+++ b/base/threading/sequenced_worker_pool.h
@@ -316,6 +316,12 @@ class BASE_EXPORT SequencedWorkerPool : public TaskRunner {
   // Must be called from the same thread this object was constructed on.
   void Shutdown(int max_new_blocking_tasks_after_shutdown);
 
+  // Check if Shutdown was called for given threading pool. This method is used
+  // for aborting time consuming operation to avoid blocking shutdown.
+  //
+  // Can be called from any thread.
+  bool IsShutdownInProgress();
+
  protected:
   virtual ~SequencedWorkerPool();