Introduce bottom controls to CC and let it respond to scrolling

content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java

Index: content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java b/content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java
index a365740d33cf2b5efc4a18bcfde39d8794c092f5..68c40cb3020e9d84e69239d8c145e8839ec84036 100644
--- a/content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java
+++ b/content/public/android/java/src/org/chromium/content/browser/ContentViewClient.java
@@ -50,6 +50,14 @@ public class ContentViewClient {
     public void onOffsetsForFullscreenChanged(
             float topControlsOffsetYPix, float contentOffsetYPix) { }
 
+    /**
+     * Notifies the client that the position of the bottom bar has changed.
+     * @param bottomOffset    The Y offset of the content above the bottom bar.
+     * @param bottomTranslate How much the bottom bar has translated down on Y axis.
+     */
+    public void onBottomOffsetChanged(float bottomOffset, float bottomTranslate) {
+    }
+
     public boolean shouldOverrideKeyEvent(KeyEvent event) {
         int keyCode = event.getKeyCode();