Add UI strings for MD style download notification.

For better MD style download notification representation, we're
going to add new attributes to Notification class, and going to
use these strings.

TEST=manual
BUG=740807

Change-Id: I05a5f1a2094814b579aee886297732b0df2c56b5
Reviewed-on: https://chromium-review.googlesource.com/578752Reviewed-by: Yoshiki Iguchi <yoshiki@chromium.org>
Commit-Queue: Tetsui Ohkubo <tetsui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488184}

chrome/app/generated_resources.grd

@@ -1409,6 +1409,14 @@ From <ph name="DOWNLOAD_DOMAIN">$3<ex>example.com</ex></ph>
                  desc="Size and units downloaded, and the origin domain.">
           <ph name="DOWNLOAD_RECEIVED">$1<ex>154 MB</ex></ph> from <ph name="DOWNLOAD_DOMAIN">$2<ex>example.com</ex></ph>
         </message>
+        <message name="IDS_DOWNLOAD_NOTIFICATION_STATUS_SHORT"
+                 desc="Size and units downloaded, and the origin domain. ">
+          <ph name="DOWNLOAD_RECEIVED">$1<ex>154 MB</ex></ph> from <ph name="DOWNLOAD_DOMAIN">$2<ex>example.com</ex></ph>
+        </message>
+        <message name="IDS_DOWNLOAD_NOTIFICATION_DISPLAY_SOURCE"
+                 desc="The name of the notification source, which is download manager here. Shown in the notification header.">
+          Download manager
+        </message>
       </if>
       <message name="IDS_DOWNLOAD_STATUS_IN_PROGRESS"
                desc="Size and units downloaded, time remaining.">