Initial support for the Google Cloud Messaging API.

New gcm mojo service with Android implementation.

Temporarily checking into flutter repo until it's easier to add third
party services.

sky/services/gcm/BUILD.gn

+# 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.
+
+# TODO(mpcomplete): move this to a separate repo. Doesn't belong in the main
+# Flutter repo.
+
+import("//mojo/public/tools/bindings/mojom.gni")
+
+group("gcm") {
+  deps = [
+    ":interfaces",
+  ]
+
+  if (is_android) {
+    deps += [ ":gcm_lib" ]
+  }
+}
+
+mojom("interfaces") {
+  sources = [
+    "gcm.mojom",
+  ]
+}
+
+if (is_android) {
+  import("//build/config/android/config.gni")
+  import("//build/config/android/rules.gni")
+
+  android_library("gcm_lib") {
+    java_files = [
+      "src/org/domokit/gcm/GcmListenerService.java",
+      "src/org/domokit/gcm/InstanceIDListenerService.java",
+      "src/org/domokit/gcm/RegistrationIntentService.java",
+    ]
+
+    deps = [
+      "//base:base_java",
+      "//mojo/java",
+      "//mojo/public/java:bindings",
+      "//mojo/public/java:system",
+      ":interfaces_java",
+      google_play_services_library,
+    ]
+  }
+}

sky/services/gcm/gcm.mojom

+// 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.
+
+[DartPackage="sky_services"]
+module gcm;
+
+[ServiceName="gcm::GcmListener"]
+interface GcmListener {
+  OnMessageReceived(string from, string jsonMessage);
+};
+
+[ServiceName="gcm::GcmService"]
+interface GcmService {
+  // senderId is the project_number from google-services.json.
+  // token should be saved and remembered - you only need to register your app
+  // once. I don't understand how this token is used, though.
+  Register(string senderId, GcmListener listener) => (string token);
+  SubscribeTopics(string token, array<string> topics);
+  UnsubscribeTopics(string token, array<string> topics);
+};

sky/services/gcm/src/org/domokit/gcm/GcmListenerService.java

+// 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.domokit.gcm;
+
+import android.os.Bundle;
+import android.util.Log;
+
+import java.util.Set;
+import org.json.JSONObject;
+import org.json.JSONException;
+
+public class GcmListenerService extends com.google.android.gms.gcm.GcmListenerService {
+    private static final String TAG = "GcmListenerService";
+
+    @Override
+    public void onMessageReceived(String from, Bundle data) {
+        // Convert the data Bundle to JSON.
+        JSONObject json = new JSONObject();
+        Set<String> keys = data.keySet();
+        for (String key : keys) {
+            try {
+                json.put(key, JSONObject.wrap(data.get(key)));
+            } catch(JSONException e) {
+                Log.d(TAG, "Failed to convert GCM message to JSON: " + e);
+            }
+        }
+
+        RegistrationIntentService.notifyMessageReceived(from, json.toString());
+    }
+}

sky/services/gcm/src/org/domokit/gcm/InstanceIDListenerService.java

+// 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.domokit.gcm;
+
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
+import android.util.Log;
+
+import com.google.android.gms.iid.InstanceID;
+
+public class InstanceIDListenerService extends com.google.android.gms.iid.InstanceIDListenerService {
+    /**
+     * Called if InstanceID token is updated. This may occur if the security of
+     * the previous token had been compromised. This call is initiated by the
+     * InstanceID provider.
+     */
+    @Override
+    public void onTokenRefresh() {
+        // TODO(mpcomplete): need to notify Dart app?
+        // Fetch updated Instance ID token and notify our app's server of any changes (if applicable).
+        Intent intent = new Intent(this, RegistrationIntentService.class);
+        startService(intent);
+    }
+}

sky/services/gcm/src/org/domokit/gcm/RegistrationIntentService.java

+// 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.domokit.gcm;
+
+import android.app.IntentService;
+import android.content.Context;
+import android.content.Intent;
+import android.util.Log;
+
+import com.google.android.gms.gcm.GcmPubSub;
+import com.google.android.gms.gcm.GoogleCloudMessaging;
+import com.google.android.gms.iid.InstanceID;
+
+import java.io.IOException;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.mojo.system.MojoException;
+import org.chromium.mojom.gcm.GcmListener;
+import org.chromium.mojom.gcm.GcmService;
+
+public class RegistrationIntentService extends IntentService {
+    private static final String TAG = "RegistrationIntentService";
+    private static final String REGISTER_EXTRA = "register";
+    private static final String TOKEN_EXTRA = "token";
+    private static final String SUBSCRIBE_EXTRA = "subscribe";
+    private static final String UNSUBSCRIBE_EXTRA = "unsubscribe";
+
+    private static GcmListener sListener;
+    private static GcmService.RegisterResponse sRegisterResponse;
+
+    public static class MojoService implements GcmService {
+        private Context context;
+
+        public MojoService(Context context) {
+            this.context = context;
+        }
+
+        @Override
+        public void close() {}
+
+        @Override
+        public void onConnectionError(MojoException e) {}
+
+        @Override
+        public void register(String senderId, GcmListener listener, RegisterResponse response) {
+            if (checkPlayServices()) {
+                // Start IntentService to register this application with GCM.
+                RegistrationIntentService.sListener = listener;
+                RegistrationIntentService.sRegisterResponse = response;
+                Intent intent = new Intent(context, RegistrationIntentService.class);
+                intent.putExtra(REGISTER_EXTRA, senderId);
+                context.startService(intent);
+            }
+        }
+
+        public void subscribeTopics(String token, String[] topics) {
+            Intent intent = new Intent(context, RegistrationIntentService.class);
+            intent.putExtra(TOKEN_EXTRA, token);
+            intent.putExtra(SUBSCRIBE_EXTRA, topics);
+            context.startService(intent);
+        }
+
+        public void unsubscribeTopics(String token, String[] topics) {
+            Intent intent = new Intent(context, RegistrationIntentService.class);
+            intent.putExtra(TOKEN_EXTRA, token);
+            intent.putExtra(UNSUBSCRIBE_EXTRA, topics);
+            context.startService(intent);
+        }
+
+        private boolean checkPlayServices() {
+            // TODO(mpcomplete): implement? This would check if the user has the Google Play Services
+            // library installed, and if not, prompt them to download it.
+            return true;
+        }
+    }
+
+    public RegistrationIntentService() {
+        super(TAG);
+    }
+
+    public static void notifyMessageReceived(final String from, final String message) {
+        ThreadUtils.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                if (sListener != null)
+                    sListener.onMessageReceived(from, message);
+            }
+        });
+    }
+
+    public static void notifyRegistered(final String token) {
+        ThreadUtils.runOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                if (sRegisterResponse != null)
+                    sRegisterResponse.call(token);
+            }
+        });
+    }
+
+    @Override
+    protected void onHandleIntent(Intent intent) {
+        try {
+            if (intent.hasExtra(REGISTER_EXTRA)) {
+                register(intent.getStringExtra(REGISTER_EXTRA));
+            } else if (intent.hasExtra(SUBSCRIBE_EXTRA)) {
+              subscribeTopics(
+                  intent.getStringExtra(TOKEN_EXTRA),
+                  intent.getStringArrayExtra(SUBSCRIBE_EXTRA));
+            } else if (intent.hasExtra(UNSUBSCRIBE_EXTRA)) {
+              unsubscribeTopics(
+                  intent.getStringExtra(TOKEN_EXTRA),
+                  intent.getStringArrayExtra(UNSUBSCRIBE_EXTRA));
+            } else {
+              Log.d(TAG, "Unexpected intent.");
+            }
+        } catch (Exception e) {
+            Log.d(TAG, "Failed to process GCM request", e);
+        }
+    }
+
+    private void register(String senderId) {
+        try {
+            InstanceID instanceID = InstanceID.getInstance(this);
+            String token = instanceID.getToken(senderId,
+                GoogleCloudMessaging.INSTANCE_ID_SCOPE, null);
+            notifyRegistered(token);
+        } catch (Exception e) {
+            Log.d(TAG, "Failed to complete token refresh", e);
+            // TODO(mpcomplete): callback error code.
+        }
+    }
+
+    private void subscribeTopics(String token, String[] topics) throws IOException {
+        GcmPubSub pubSub = GcmPubSub.getInstance(this);
+        for (String topic : topics) {
+            pubSub.subscribe(token, "/topics/" + topic, null);
+        }
+    }
+
+    private void unsubscribeTopics(String token, String[] topics) throws IOException {
+        GcmPubSub pubSub = GcmPubSub.getInstance(this);
+        for (String topic : topics) {
+            pubSub.unsubscribe(token, "/topics/" + topic);
+        }
+    }
+}