Restrict throbber messages to SingleSuggestionView objects.

chrome/browser/ui/cocoa/web_intent_sheet_controller.mm

Index: chrome/browser/ui/cocoa/web_intent_sheet_controller.mm
diff --git a/chrome/browser/ui/cocoa/web_intent_sheet_controller.mm b/chrome/browser/ui/cocoa/web_intent_sheet_controller.mm
index d016793432d74b4e13378306be7ced8e71750fbe..7d3db77ea4a389dfc3d76727b7242b122f268afc 100644
--- a/chrome/browser/ui/cocoa/web_intent_sheet_controller.mm
+++ b/chrome/browser/ui/cocoa/web_intent_sheet_controller.mm
@@ -410,16 +410,21 @@ NSButton* CreateHyperlinkButton(NSString* title, const NSRect& frame) {
 
 - (void)startThrobberForRow:(NSInteger)index {
   for (SingleSuggestionView* row in [self subviews]) {
-    [row setEnabled:NO];
-    if ([row tag] == index)
-      [row startThrobber];
+    if ([row isMemberOfClass:[SingleSuggestionView class]]) {
+      [row setEnabled:NO];
+      if ([row tag] == index) {
+        [row startThrobber];
+      }
+    }
   }
 }
 
 - (void)stopThrobber {
   for (SingleSuggestionView* row in [self subviews]) {
-    [row stopThrobber];
-    [row setEnabled:YES];
+    if ([row isMemberOfClass:[SingleSuggestionView class]]) {
+      [row stopThrobber];
+      [row setEnabled:YES];
+    }
   }
 }