[ios] Adds period to CBD warning message.

Bug: 870150
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Idfed72db1f82009e002fb5ed1a6c76427eb0b697
Reviewed-on: https://chromium-review.googlesource.com/1170185Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582194}

ios/chrome/app/strings/ios_strings.grd

@@ -514,7 +514,7 @@ locale.  The strings in this file are specific to iOS.
         Clear Browsing Data
       </message>
       <message name="IDS_IOS_CONFIRM_CLEAR_BUTTON_TITLE" desc="Title for the UIAlertController indicating browsing data selected will be removed. [Length: 20em] [iOS only]">
-        The items you selected will be removed
+        The items you selected will be removed.
       </message>
       <message name="IDS_IOS_CONFIRM_CLEAR_BUTTON" desc="Accessibility label for the button used to confirm clearing data. [iOS only]">
         Confirm Clear Browsing Data