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This CL adds new material design icon to locale change notification.
This CL also adds the notification title and shortens the message
based on UX review (https://crbug.com/726241#c20).

The icon and the accent color is effective only when
chrome://flags/#enable-message-center-new-style-notification
is Enabled (which is ToT default).

TEST=manual
BUG=726241

Change-Id: I16ac609c9f453064e27441c149ef2e4bcfa08d31
Reviewed-on: https://chromium-review.googlesource.com/662917Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501514}