Remove RenderThreadImpl::Shutdown

base/at_exit.h

Index: base/at_exit.h
diff --git a/base/at_exit.h b/base/at_exit.h
index 02e18ed9eb7508c1d3ffce38e175214c7c60f9e4..6bf3f50350ec7f76d2f0193aeafb3ee84975517a 100644
--- a/base/at_exit.h
+++ b/base/at_exit.h
@@ -49,6 +49,10 @@ class BASE_EXPORT AtExitManager {
   // is possible to register new callbacks after calling this function.
   static void ProcessCallbacksNow();
 
+  // Disable all registered at-exit callbacks. This is used only in a single-
+  // process mode.
+  static void DisableAllAtExitManagers();
+
  protected:
   // This constructor will allow this instance of AtExitManager to be created
   // even if one already exists.  This should only be used for testing!