Fix crash in ProfileMenuController::validateMenuItem.

chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm

Index: chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm
diff --git a/chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm b/chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm
index 437bed15fe87fef70434fae95bd5058c3048dc8a..f5930d5493c506b937ba80ad714c4c7b2dcc53cf 100644
--- a/chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm
+++ b/chrome/browser/ui/cocoa/profiles/profile_menu_controller.mm
@@ -5,6 +5,7 @@
 #import "chrome/browser/ui/cocoa/profiles/profile_menu_controller.h"
 
 #include "base/mac/scoped_nsobject.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/profiles/avatar_menu.h"
@@ -25,6 +26,17 @@
 #include "ui/base/l10n/l10n_util_mac.h"
 #include "ui/gfx/image/image.h"
 
+namespace {
+  enum ValidateMenuItemSelector {

[Alexei Svitkine (slow), 2015/04/22 16:55:25]

Don't indent within namespace. Add a comment that this is used in an UMA macro
and that entries shouldn't be renumbered or removed.

[anthonyvd, 2015/04/23 14:49:01]

Done.

+    UNKNOWN_SELECTOR,
+    NEW_PROFILE,
+    EDIT_PROFILE,
+    SWITCH_PROFILE_MENU,
+    SWITCH_PROFILE_DOCK,
+    MAX_VALIDATE_MENU_SELECTOR,
+  };
+}
+
 @interface ProfileMenuController (Private)
 - (void)initializeMenu;
 @end
@@ -169,8 +181,30 @@ class Observer : public chrome::BrowserListObserver,
            [menuItem action] != @selector(editProfile:);
   }
 
-  const AvatarMenu::Item& itemData = avatarMenu_->GetItemAt(
-      avatarMenu_->GetActiveProfileIndex());
+  size_t index = avatarMenu_->GetActiveProfileIndex();
+  if (avatarMenu_->GetNumberOfItems() <= index) {
+    ValidateMenuItemSelector current_selector = UNKNOWN_SELECTOR;
+    if ([menuItem action] == @selector(newProfile:))
+      current_selector = NEW_PROFILE;
+    else if ([menuItem action] == @selector(editProfile:))
+      current_selector = EDIT_PROFILE;
+    else if ([menuItem action] == @selector(switchToProfileFromMenu:))
+      current_selector = SWITCH_PROFILE_MENU;
+    else if ([menuItem action] == @selector(switchToProfileFromDock:))
+      current_selector = SWITCH_PROFILE_DOCK;
+    UMA_HISTOGRAM_ENUMERATION("ValidateMenuItemInvalidIndexSelector",

[Alexei Svitkine (slow), 2015/04/22 16:55:25]

Histograms use a dotted naming notation - e.g. Foo.Bar.Baz. Please update these
names to use that, nesting them under some existing category (Profiles?).

[anthonyvd, 2015/04/23 14:49:01]

Done.

+                              current_selector,
+                              MAX_VALIDATE_MENU_SELECTOR);
+    UMA_HISTOGRAM_CUSTOM_COUNTS("ValidateMenuItemInvalidIndexProfileCount",
+                                avatarMenu_->GetNumberOfItems(),
+                                1, 20, 20);
+    UMA_HISTOGRAM_BOOLEAN("ValidateMenuItemInvalidIndexIsGuest",
+                          activeProfile->IsGuestSession());
+
+    return NO;
+  }
+
+  const AvatarMenu::Item& itemData = avatarMenu_->GetItemAt(index);
   if ([menuItem action] == @selector(switchToProfileFromDock:) ||
       [menuItem action] == @selector(switchToProfileFromMenu:)) {
     if (!itemData.legacy_supervised)