[Chromecast] Use Dpad left/right to navigate backward/forward on ATV

-Make REVERSE/FORWARD buttons have the same behavior as LEFT/RIGHT buttons.
-The internal part is in eureka-internal/187704

BUG=internal b/71719665

Test=cast movie from Google Play Movie and press the button on the remote.

Change-Id: If9ff5132851df7ac00e81fd5fcca73725b3c0307
Reviewed-on: https://chromium-review.googlesource.com/c/1150804
Commit-Queue: Ziyang Cheng <ziyangch@chromium.org>
Reviewed-by: Simeon Anfinrud <sanfin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603687}

chromecast/browser/android/apk/src/org/chromium/chromecast/shell/CastWebContentsActivity.java

@@ -236,7 +236,10 @@ public class CastWebContentsActivity extends Activity {
 
         // Similar condition for all single-click events.
         if (action == KeyEvent.ACTION_DOWN && event.getRepeatCount() == 0) {
-            if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER
+            if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER || keyCode == KeyEvent.KEYCODE_DPAD_LEFT
+                    || keyCode == KeyEvent.KEYCODE_MEDIA_REWIND
+                    || keyCode == KeyEvent.KEYCODE_DPAD_RIGHT
+                    || keyCode == KeyEvent.KEYCODE_MEDIA_FAST_FORWARD
                     || keyCode == KeyEvent.KEYCODE_MEDIA_PLAY_PAUSE
                     || keyCode == KeyEvent.KEYCODE_MEDIA_PLAY
                     || keyCode == KeyEvent.KEYCODE_MEDIA_PAUSE