-Wuninitialized fixes

chrome/browser/ui/cocoa/about_window_controller.mm

Index: chrome/browser/ui/cocoa/about_window_controller.mm
diff --git a/chrome/browser/ui/cocoa/about_window_controller.mm b/chrome/browser/ui/cocoa/about_window_controller.mm
index 45a4df73342e388a04f966e7a0457da0022ad957..eefc1f7c78fcee04beb6fbba7bbd350906a77e59 100644
--- a/chrome/browser/ui/cocoa/about_window_controller.mm
+++ b/chrome/browser/ui/cocoa/about_window_controller.mm
@@ -522,6 +522,7 @@ static BOOL recentShownUserActionFailedStatus = NO;
       // be replaced with the #else block.  For now, just leave the messaging
       // alone.  http://b/2290009.
       updateMessage = false;
+      message = nil;  // clang (no pr)
 #else
       // The visibility may be changing.
       [self adjustUpdateUIVisibility];