Migrate ProcessesEventRouter to the new task manager

chrome/browser/task_management/providers/task_provider_observer.h

Index: chrome/browser/task_management/providers/task_provider_observer.h
diff --git a/chrome/browser/task_management/providers/task_provider_observer.h b/chrome/browser/task_management/providers/task_provider_observer.h
index 72f8696615d8ef9d0e7f827eb5de24ccf96a16cb..db95bd290b7ae2f132e412101ecd01ac242829e2 100644
--- a/chrome/browser/task_management/providers/task_provider_observer.h
+++ b/chrome/browser/task_management/providers/task_provider_observer.h
@@ -24,6 +24,10 @@ class TaskProviderObserver {
   // the observer and references to it must not be kept.
   virtual void TaskRemoved(Task* task) = 0;
 
+  // This notifies of the event that |task| has become unresponsive. This event
+  // is only for tasks representing renderer processes.
+  virtual void TaskUnresponsive(Task* task) {}
+
  private:
   DISALLOW_COPY_AND_ASSIGN(TaskProviderObserver);
 };