[Start Surface] Fix feed header.

Screenshots here: https://drive.google.com/open?id=1jqvHaKpi_7gKqnBO7tbOXlBcB_xTLjMQ

Bug: 1028491

Change-Id: I854da2f726e0118dde7815f08457fc95e6cf8c95
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1944530Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Commit-Queue: Mia Glaese <glamia@chromium.org>
Cr-Commit-Position: refs/heads/master@{#720455}

chrome/android/features/start_surface/internal/java/explore_res/layout/ss_feed_header.xml

@@ -11,6 +11,7 @@
     android:orientation="horizontal"
     android:paddingTop="8dp"
     android:paddingBottom="8dp"
+    android:paddingEnd="8dp"
     android:gravity="center_vertical">
 
     <TextView