[Sync] Introduce GmsCoreSyncListener.

chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java b/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
index 4ae346a23430f3507dad4acd29295bc785c5c32f..92bcd1cb25f07012974916888267736947cd7034 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ChromeApplication.java
@@ -84,6 +84,7 @@ import org.chromium.chrome.browser.services.GoogleServicesManager;
 import org.chromium.chrome.browser.share.ShareHelper;
 import org.chromium.chrome.browser.smartcard.EmptyPKCS11AuthenticationManager;
 import org.chromium.chrome.browser.smartcard.PKCS11AuthenticationManager;
+import org.chromium.chrome.browser.sync.GmsCoreSyncListener;
 import org.chromium.chrome.browser.sync.SyncController;
 import org.chromium.chrome.browser.tab.AuthenticatorNavigationInterceptor;
 import org.chromium.chrome.browser.tab.Tab;
@@ -789,6 +790,14 @@ public class ChromeApplication extends ContentApplication {
     }
 
     /**
+     * @return An instance of GmsCoreSyncListener to notify GmsCore of sync encryption key changes.
+     *         Will be null if one is unavailable.
+     */
+    public GmsCoreSyncListener createGmsCoreSyncListener() {
+        return null;
+    }
+
+    /**
      * @return An instance of AppDetailsDelegate that can be queried about app information for the
      *         App Banner feature.  Will be null if one is unavailable.
      */