Rewrite AndroidSyncSettings to be significantly simpler.

sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java

Index: sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
diff --git a/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java b/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
index 3e0b8ca7ae5eca47c177588e86632deefa21daac..fde40a5d9e1b90c2d936a48d6320e88d05b5a86e 100644
--- a/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
+++ b/sync/android/java/src/org/chromium/sync/signin/ChromeSigninController.java
@@ -14,8 +14,16 @@ import com.google.ipc.invalidation.external.client.contrib.MultiplexingGcmListen
 
 import org.chromium.base.ObserverList;
 import org.chromium.base.VisibleForTesting;
+import org.chromium.sync.AndroidSyncSettings;
 
+/**
+ * Caches the signed-in username in the app prefs.
+ */
 public class ChromeSigninController {
+
+    /**
+     * Interface for listening to signin events from ChromeSigninController.
+     */
     public interface Listener {
         /**
          * Called when the user signs out of Chrome.
@@ -36,10 +44,13 @@ public class ChromeSigninController {
 
     private final ObserverList<Listener> mListeners = new ObserverList<Listener>();
 
+    private final AndroidSyncSettings mAndroidSyncSettings;
+
     private boolean mGcmInitialized;
 
     private ChromeSigninController(Context context) {
         mApplicationContext = context.getApplicationContext();
+        mAndroidSyncSettings = AndroidSyncSettings.get(context);
     }
 
     /**
@@ -73,6 +84,7 @@ public class ChromeSigninController {
         PreferenceManager.getDefaultSharedPreferences(mApplicationContext).edit()
                 .putString(SIGNED_IN_ACCOUNT_KEY, accountName)
                 .apply();
+        mAndroidSyncSettings.updateAccount(getSignedInUser());

[nyquist, 2015/02/06 03:03:57]

Could this be done by SigninManager instead? I think we should merge
ChromeSigninController and SigninManager into one class. It's not for this CL
though. Only tests and the SigninManager currently calls this method, so it
should be OK to move this to SigninManager later.
We just need to take care about whether native has been loaded or not.
InvalidationControllerTest and AndroidSyncSettingsTest currently don't load
native.

Could you add a TODO or file a bug for that?

[maxbogue, 2015/02/10 09:20:00]

Added a TODO for this line. I can file a bug for merging the whole class if
you'd like.

     }
 
     public void clearSignedInUser() {