Add media controls in media notification

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 b212a68e0ee4a904b4293bbc7ea1ef5cc1133e9b..c45005cc303536045ab926680af36c0ec2a2dd5f 100644
--- a/chrome/android/java/strings/android_chrome_strings.grd
+++ b/chrome/android/java/strings/android_chrome_strings.grd
@@ -1892,6 +1892,12 @@ To obtain new licenses, connect to the internet and play your downloaded content
       <message name="IDS_ACCESSIBILITY_STOP" desc="Content description for the stop button that stops playing the media.">
         Stop
       </message>
+      <message name="IDS_ACCESSIBILITY_PREVIOUS_TRACK" desc="Content description for the previous track button that switchs media to the previous track.">
+        Previous track
+      </message>
+      <message name="IDS_ACCESSIBILITY_NEXT_TRACK" desc="Content description for the next track button that switchs media to the next track.">
+        Next track
+      </message>
 
       <!-- New Tab Page strings -->
       <message name="IDS_NTP_BOOKMARKS" desc="Text for bookmarks button [CHAR-LIMIT=20]">