[rAC, OSX] Use bubble windows for error messages.

chrome/browser/ui/cocoa/base_bubble_controller.mm

Index: chrome/browser/ui/cocoa/base_bubble_controller.mm
diff --git a/chrome/browser/ui/cocoa/base_bubble_controller.mm b/chrome/browser/ui/cocoa/base_bubble_controller.mm
index fad938f381753510dd6ebe7abd54b47d80ef7c56..42b62b0d77101680a785a53f5d8759f7a8546e19 100644
--- a/chrome/browser/ui/cocoa/base_bubble_controller.mm
+++ b/chrome/browser/ui/cocoa/base_bubble_controller.mm
@@ -29,6 +29,7 @@
 @synthesize anchorPoint = anchor_;
 @synthesize bubble = bubble_;
 @synthesize shouldOpenAsKeyWindow = shouldOpenAsKeyWindow_;
+@synthesize shouldCloseOnResignKey = shouldCloseOnResignKey_;
 
 - (id)initWithWindowNibPath:(NSString*)nibPath
                parentWindow:(NSWindow*)parentWindow
@@ -72,6 +73,7 @@
     parentWindow_ = parentWindow;
     anchor_ = anchoredAt;
     shouldOpenAsKeyWindow_ = YES;
+    shouldCloseOnResignKey_ = YES;
 
     DCHECK(![[self window] delegate]);
     [theWindow setDelegate:self];
@@ -184,7 +186,7 @@
 - (void)windowDidResignKey:(NSNotification*)notification {
   NSWindow* window = [self window];
   DCHECK_EQ([notification object], window);
-  if ([window isVisible]) {
+  if ([window isVisible] && [self shouldCloseOnResignKey]) {
     // If the window isn't visible, it is already closed, and this notification
     // has been sent as part of the closing operation, so no need to close.
     [self close];