[Custom Tabs]Add API for updating action button in service

chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java
index d91d28ddc0677932261584c3f0256cb35874dabd..d16056dba554af5e35787f8ab3fb445a133c202d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/toolbar/ToolbarManager.java
@@ -618,14 +618,15 @@ public class ToolbarManager implements ToolbarTabController, UrlFocusChangeListe
     }
 
     /**
-     * Adds a custom action button to the {@link Toolbar} if it is supported.
-     * @param drawable     The {@link Drawable} to use as the background for the button.
-     * @param description  The content description for the custom action button.
-     * @param listener     The {@link OnClickListener} to use for clicks to the button.
+     * Sets/adds a custom action button to the {@link Toolbar} if it is supported. If there is
+     * already an action button, update the button instead.
+     * @param drawable The {@link Drawable} to use as the background for the button.
+     * @param description The content description for the custom action button.
+     * @param listener The {@link OnClickListener} to use for clicks to the button.
      */
-    public void addCustomActionButton(Drawable drawable, String description,
+    public void setCustomActionButton(Drawable drawable, String description,
             OnClickListener listener) {
-        mToolbar.addCustomActionButton(drawable, description, listener);
+        mToolbar.setCustomActionButton(drawable, description, listener);
     }
 
     /**