[Android] Fix bookmark row vertical alignment.

Fixed the followings:

1. Bookmark row text was aligned to the top.
(regression from https://crrev.com/2cb98653338e23e4f31ade78de2ef872e697b2bc)

2. On offline section, selection-highlighting was not symmetric
   vertically.

BUG=577996

Review URL: https://codereview.chromium.org/1636773002

Cr-Commit-Position: refs/heads/master@{#371397}

chrome/android/java/res/layout/eb_row_content.xml

@@ -26,6 +26,7 @@
             android:layout_width="0dp"
             android:layout_height="48dp"
             android:layout_weight="1"
+            android:gravity="center_vertical"
             android:orientation="vertical" >
 
             <TextView

chrome/android/java/src/org/chromium/chrome/browser/enhancedbookmarks/EnhancedBookmarkBookmarkRow.java

@@ -99,12 +99,12 @@ public class EnhancedBookmarkBookmarkRow extends EnhancedBookmarkRow implements
         TextView textView = (TextView) findViewById(R.id.offline_page_size);
         View bookmarkRowView = findViewById(R.id.bookmark_row);
         if (offlinePage != null) {
-            int bottomPadding = textView.getResources().getDimensionPixelSize(
+            int verticalPadding = textView.getResources().getDimensionPixelSize(
                     R.dimen.offline_page_item_vertical_spacing);
             textView.setText(Formatter.formatFileSize(getContext(), offlinePage.getFileSize()));
             // Get the embedded bookmark_row layout, and add padding.  This is because the entries
             // in filter view are larger (contain more items) than normal bookmark view.
-            bookmarkRowView.setPadding(0, 0, 0, bottomPadding);
+            bookmarkRowView.setPadding(0, verticalPadding / 2, 0, verticalPadding / 2);
             textView.setVisibility(View.VISIBLE);
         } else {
             textView.setVisibility(View.GONE);