Add APIs to CustomTabsIntent and CustomTabsSession for Bottombar

customtabs/src/android/support/customtabs/CustomTabsSession.java

Index: customtabs/src/android/support/customtabs/CustomTabsSession.java
diff --git a/customtabs/src/android/support/customtabs/CustomTabsSession.java b/customtabs/src/android/support/customtabs/CustomTabsSession.java
index a51cf0ea1eca8e2a59a5bf32e74f3de554cd341b..09c796b2b583abb864b9995fec4a846956b8e848 100644
--- a/customtabs/src/android/support/customtabs/CustomTabsSession.java
+++ b/customtabs/src/android/support/customtabs/CustomTabsSession.java
@@ -68,14 +68,23 @@ public final class CustomTabsSession {
     }
 
     /**
-     * Update the visuals for the button on a custom tab. Will only succeed if the given
-     * session is the active one in browser.
+     * @see {@link #setActionButton(Bitmap, String)}
+     */
+    public boolean setActionButton(@NonNull Bitmap icon, @NonNull String description) {
+        return setActionButton(CustomTabsIntent.TOOLBAR_ACTION_BUTTON_ID, icon, description);
+    }
+
+    /**
+     * Updates the visuals for custom action buttons. Will only succeed if the given
+     * session is the active one in browser and the given id is valid.
+     * @param id            The id for the button to update.
      * @param icon          The new icon of the action button.
      * @param description   Content description of the action button.
      * @return              Whether the update succeeded.
      */
-    public boolean setActionButton(@NonNull Bitmap icon, @NonNull String description) {
+    public boolean setActionButton(int id, @NonNull Bitmap icon, @NonNull String description) {
         Bundle bundle = new Bundle();
+        bundle.putInt(CustomTabsIntent.KEY_ID, id);
         bundle.putParcelable(CustomTabsIntent.KEY_ICON, icon);
         bundle.putString(CustomTabsIntent.KEY_DESCRIPTION, description);