Add sign-in and token retrieval to Blimp

blimp/client/android/java/src/org/chromium/blimp/auth/TokenSourceImpl.java

Index: blimp/client/android/java/src/org/chromium/blimp/auth/TokenSourceImpl.java
diff --git a/blimp/client/android/java/src/org/chromium/blimp/auth/TokenSourceImpl.java b/blimp/client/android/java/src/org/chromium/blimp/auth/TokenSourceImpl.java
new file mode 100644
index 0000000000000000000000000000000000000000..43d6a74b836d8717a857692e90cc1af0f27b3c61
--- /dev/null
+++ b/blimp/client/android/java/src/org/chromium/blimp/auth/TokenSourceImpl.java
@@ -0,0 +1,171 @@
+// Copyright 2015 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.auth;
+
+import android.accounts.Account;
+import android.accounts.AccountManager;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.AsyncTask;
+import android.preference.PreferenceManager;
+
+import com.google.android.gms.auth.GoogleAuthException;
+import com.google.android.gms.auth.GoogleAuthUtil;
+import com.google.android.gms.auth.GooglePlayServicesAvailabilityException;
+import com.google.android.gms.auth.UserRecoverableNotifiedException;
+import com.google.android.gms.common.ConnectionResult;
+
+import org.chromium.base.Log;
+
+import org.chromium.blimp.R;
+
+import java.io.IOException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * An implementation of TokenSource that handles querying {@link GoogleAuthUtil} for a valid
+ * authentication token for a particular user account.  The user account will be saved as an
+ * application preference once set.  See {@link TokenSource} for information on how callers know
+ * whether or not an account is set and how they set one.
+ */
+public class TokenSourceImpl implements TokenSource {
+    private static final String ACCOUNT_NAME_PREF = "BlimpAccount";
+    private static final String ACCOUNT_SCOPE =

[nyquist, 2015/09/29 23:38:40]

Nit: OAUTH2_SCOPE
Could you also add a comment explaining why the scope is prefixed with
'oauth2:'?

[David Trainor- moved to gerrit, 2015/10/05 15:19:07]

Done.

+            "oauth2:https://www.googleapis.com/auth/userinfo.email";
+    private static final String ACCOUNT_TYPE = "com.google";
+    private static final String TAG = "cr_BlimpTokenSource";

[nyquist, 2015/09/29 23:38:40]

Nit: s/cr\_//

[David Trainor- moved to gerrit, 2015/10/05 15:19:07]

Done.

+
+    private final Context mAppContext;
+
+    private TokenSource.Callback mCallback;
+    private AsyncTask<String, Void, String> mTokenQueryTask;
+
+    /**
+     * Creates a {@link TokenSourceImpl} that will load and save account information from the
+     * application {@link Context} given by {@code context}.
+     * @param context
+     */
+    public TokenSourceImpl(Context context) {
+        mAppContext = context.getApplicationContext();
+    }
+
+    // TokenSource implementation.
+    @Override
+    public void destroy() {
+        if (isRetrievingToken()) {
+            mTokenQueryTask.cancel(true);
+        }
+    }
+
+    @Override
+    public void setCallback(TokenSource.Callback callback) {
+        mCallback = callback;
+    }
+
+    @Override
+    public void getToken() {
+        if (isRetrievingToken()) {
+            mTokenQueryTask.cancel(true);
+            mTokenQueryTask = null;
+        }
+
+        if (mCallback == null) return;
+
+        // Find the current account tracked by settings.
+        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(mAppContext);
+        String accountName = preferences.getString(ACCOUNT_NAME_PREF, null);
+
+        if (accountName == null || !doesAccountExist(accountName)) {
+            // Remove any old preference value in case the account is invalid.
+            preferences.edit().remove(ACCOUNT_NAME_PREF).commit();
+
+            // Trigger account selection.
+            mCallback.onNeedsAccountToBeSelected(getAccountChooserIntent());
+            return;
+        }
+
+        mTokenQueryTask = new TokenQueryTask();
+        mTokenQueryTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, accountName);
+    }
+
+    @Override
+    public boolean isRetrievingToken() {
+        return mTokenQueryTask != null && mTokenQueryTask.getStatus() == AsyncTask.Status.RUNNING;
+    }
+
+    @Override
+    public int tokenIsInvalid(String token) {
+        // TODO(dtrainor): Handle failure cases for tokenIsInvalid.
+        try {
+            GoogleAuthUtil.clearToken(mAppContext, token);
+        } catch (GooglePlayServicesAvailabilityException ex) {
+            return ex.getConnectionStatusCode();
+        } catch (GoogleAuthException ex) {
+            Log.e(TAG, "Authentication exception during token query.");
+            return ConnectionResult.SIGN_IN_FAILED;
+        } catch (IOException ex) {
+            Log.e(TAG, "IOException during token query.");
+            return ConnectionResult.SIGN_IN_FAILED;
+        }
+        return ConnectionResult.SUCCESS;
+    }
+
+    @Override
+    public void onAccountSelected(Intent data) {
+        String accountName = data.getStringExtra(AccountManager.KEY_ACCOUNT_NAME);
+        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(mAppContext);
+        preferences.edit().putString(ACCOUNT_NAME_PREF, accountName).commit();
+    }
+
+    @SuppressWarnings("deprecation")
+    private Intent getAccountChooserIntent() {
+        // TODO(dtrainor): Change this to com.google.android.gms.common.AccountPicker.
+        return AccountManager.newChooseAccountIntent(null, null, new String[] {ACCOUNT_TYPE}, false,
+                mAppContext.getString(R.string.signin_chooser_description), null, null, null);
+    }
+
+    private boolean doesAccountExist(String accountName) {
+        Account[] accounts = AccountManager.get(mAppContext).getAccountsByType(ACCOUNT_TYPE);
+        for (Account account : accounts) {
+            if (account.name.equals(accountName)) return true;
+        }
+
+        return false;
+    }
+
+    private class TokenQueryTask extends AsyncTask<String, Void, String> {
+        private final AtomicBoolean mIsRecoverable = new AtomicBoolean();
+
+        @Override
+        protected String doInBackground(String... params) {
+            try {
+                return GoogleAuthUtil.getTokenWithNotification(
+                        mAppContext, params[0], ACCOUNT_SCOPE, null);
+            } catch (UserRecoverableNotifiedException ex) {
+                // TODO(dtrainor): Does it make sense for this to be true if we can't recover until
+                // the user performs some action?
+                mIsRecoverable.set(true);
+            } catch (IOException ex) {
+                mIsRecoverable.set(true);
+            } catch (GoogleAuthException ex) {
+                mIsRecoverable.set(false);
+            }
+            return null;
+        }
+
+        @Override
+        protected void onPostExecute(String result) {

[nyquist, 2015/09/29 23:38:40]

Nit: s/result/token/

[David Trainor- moved to gerrit, 2015/10/05 15:19:07]

Done.

+            if (mCallback == null || isCancelled()) return;
+
+            if (result == null) {
+                mCallback.onTokenUnavailable(mIsRecoverable.get());
+            } else {
+                mCallback.onTokenReceived(result);
+            }
+            if (mTokenQueryTask == TokenQueryTask.this) mTokenQueryTask = null;
+        }
+    }
+}