Update the rich content UI to meet the UX design version 2.

1. Using the footerPreference component for the interface
android:desription.
2. Remove the redundant and unused codes.
3. Remove the ripple effect for AnimatedImagePreference.

Bug: 142532186
Test: manual test
Change-Id: I547ed7611b40d8b7bee4c4350b00bd4987768950

src/com/android/settings/accessibility/HtmlTextPreference.java

@@ -32,7 +32,6 @@ import java.util.regex.Pattern;
  */
 public final class HtmlTextPreference extends StaticTextPreference {
 
-    private boolean mDividerAllowedAbove = false;
     private int mFlag = Html.FROM_HTML_MODE_COMPACT;
     private Html.ImageGetter mImageGetter;
     private Html.TagHandler mTagHandler;
@@ -45,7 +44,6 @@ public final class HtmlTextPreference extends StaticTextPreference {
     @Override
     public void onBindViewHolder(PreferenceViewHolder holder) {
         super.onBindViewHolder(holder);
-        holder.setDividerAllowedAbove(mDividerAllowedAbove);
 
         final TextView summaryView = holder.itemView.findViewById(android.R.id.summary);
         if (summaryView != null && !TextUtils.isEmpty(getSummary())) {
@@ -54,18 +52,6 @@ public final class HtmlTextPreference extends StaticTextPreference {
         }
     }
 
-    /**
-     * Sets divider whether to show in preference above.
-     *
-     * @param allowed true will be drawn on above this item
-     */
-    public void setDividerAllowedAbove(boolean allowed) {
-        if (allowed != mDividerAllowedAbove) {
-            mDividerAllowedAbove = allowed;
-            notifyChanged();
-        }
-    }
-
     /**
      * Sets the flag to which text format to be applied.
      *