Blimp OAuth2 token retreival on application start up.

blimp/client/core/android/java/src/org/chromium/blimp/core/auth/Authenticator.java

Index: blimp/client/core/android/java/src/org/chromium/blimp/core/auth/Authenticator.java
diff --git a/blimp/client/core/android/java/src/org/chromium/blimp/core/auth/Authenticator.java b/blimp/client/core/android/java/src/org/chromium/blimp/core/auth/Authenticator.java
new file mode 100644
index 0000000000000000000000000000000000000000..1296685c7493c116b23fdbf9286a2c73a42d07fe
--- /dev/null
+++ b/blimp/client/core/android/java/src/org/chromium/blimp/core/auth/Authenticator.java
@@ -0,0 +1,53 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.blimp.core.auth;
+
+import android.content.Context;
+
+import org.chromium.base.CommandLine;
+import org.chromium.base.ContextUtils;
+import org.chromium.blimp.core.BlimpClientSwitches;
+import org.chromium.blimp_public.BlimpClientContext;
+import org.chromium.components.sync.signin.AccountManagerHelper;
+import org.chromium.components.sync.signin.ChromeSigninController;
+
+/**
+ * Class to request OAuth2 token for Blimp.
+ */
+public class Authenticator {
+
+    private static final String SCOPE = "oauth2:https://www.googleapis.com/auth/userinfo.email";
+
+    private BlimpClientContext mBlimpClientContext;
+
+    public Authenticator(BlimpClientContext context) {
+        mBlimpClientContext = context;
+    }
+
+    /**
+     * Request OAuth2 token for Blimp if user signed in and we don't have command line argument
+     * {@link BlimpClientSwitches#ENGINE_IP}.
+     */
+    public void getAuthToken() {
+        final Context context = ContextUtils.getApplicationContext();
+        final AccountManagerHelper accountManagerHelper = AccountManagerHelper.get(context);
+        ChromeSigninController signin = ChromeSigninController.get(context);
+
+        if (signin.isSignedIn()
+                && !CommandLine.getInstance().hasSwitch(BlimpClientSwitches.ENGINE_IP)) {
+            accountManagerHelper.getAuthToken(signin.getSignedInUser(), SCOPE,

[nyquist, 2016/08/05 17:05:07]

Since this does everything directly inside of blimp, I wonder if we should just
move this to native code instead? You could ask the delegate to get an
OAuth2TokenService. It should be able to get one through
ProfileOAuth2TokenServiceFactory::GetForProfile(Profile* profile).
That way we don't have to have any of this Java-code.

[xingliu, 2016/08/09 04:17:45]

Done.

+                    new AccountManagerHelper.GetAuthTokenCallback() {
+                        @Override
+                        public void tokenAvailable(String token) {
+                            mBlimpClientContext.connect(token);
+                        }
+
+                        @Override
+                        public void tokenUnavailable(boolean isTransientError) {

[David Trainor- moved to gerrit, 2016/08/05 15:49:09]

Will this be handled in the future CL?

[xingliu, 2016/08/05 17:17:00]

Should we show some error message and give user an option to trigger the
authentication flow again in something like snackbar or alert dialog?

+                        }
+                    });
+        }
+    }
+}