chrome/blink: Add functionality for in-product help for media elements.

chrome/android/java/strings/android_chrome_strings.grd

Index: chrome/android/java/strings/android_chrome_strings.grd
diff --git a/chrome/android/java/strings/android_chrome_strings.grd b/chrome/android/java/strings/android_chrome_strings.grd
index 70e4e9caff6a3ac5d51b896ee0440f99f13d455f..4395dc23418fc0230645f4175397be34f6955077 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -3075,7 +3075,12 @@ You must have Bluetooth and Location turned on in order to use the Physical Web.
       <message name="IDS_IPH_DATA_SAVER_DETAIL_ACCESSIBILITY_TEXT" desc="The in-product-help accessibility text to open data saver.">
         See how much data you've saved from the More Options button
       </message>
-
+      <message name="IDS_IPH_MEDIA_DOWNLOAD_TEXT" desc="The in-product-help message to download a video.">
+        Download videos to watch later
+      </message>
+      <message name="IDS_IPH_MEDIA_DOWNLOAD_ACCESSIBILITY_TEXT" desc="The in-product-help accessibility text to download a video.">
+        Download videos to watch later using the Download button

[mlamouri (slow - plz ping), 2017/07/13 21:14:27]

Are you showing this only for videos?

[Khushal, 2017/07/17 17:52:20]

Yes. I added an if check for video element in MayBeDispatchInProductHelpTrigger.

+      </message>
       <!-- Search Widget strings -->
       <message name="IDS_SEARCH_WIDGET_DEFAULT" desc="Default text for the search widget">
         Search