[Chromoting] Implement HEARTBEAT log message on webapp.

This CL sends a HEARTBEAT message from the webapp to the telemetry backend
whenever the app is launched.

This will be used to help us understand how many clients are deployed in
a percentage push.

BUG=502095

Review URL: https://codereview.chromium.org/1219043003

Cr-Commit-Position: refs/heads/master@{#336956}

remoting/remoting_webapp_files.gypi

@@ -408,6 +408,7 @@
       'webapp/base/js/oauth2.js',
       'webapp/base/js/oauth2_api.js',
       'webapp/base/js/oauth2_api_impl.js',
+      'webapp/base/js/platform.js',
       'webapp/base/js/plugin_settings.js',
       'webapp/base/js/telemetry_event_writer.js',
       'webapp/base/js/typecheck.js',

remoting/webapp/base/js/telemetry_event_writer.js

@@ -45,7 +45,7 @@ remoting.TelemetryEventWriter.Service.prototype.init = function() {
         new base.ChromeEventHook(chrome.runtime.onSuspend,
                                  this.onSuspend_.bind(this)));
 
-    this.ipc_.register(IpcNames.WRITE, this.write_.bind(this));
+    this.ipc_.register(IpcNames.WRITE, this.write.bind(this));
     this.eventWriter_.flush();
   }
   // Only listen for new incoming requests after we have loaded the pending
@@ -72,9 +72,9 @@ remoting.TelemetryEventWriter.Service.prototype.unbindSession =
  * @param {string} windowId  The source window id of the IPC.
  * @param {!Object} event  The event to be written to the server.
  */
-remoting.TelemetryEventWriter.Service.prototype.write_ =
+remoting.TelemetryEventWriter.Service.prototype.write =
     function(windowId, event) {
-  this.sessionMonitor_.onEvent(windowId, event);
+  this.sessionMonitor_.trackSessionStateChanges(windowId, event);
   this.eventWriter_.write(event);
 };
 
@@ -137,7 +137,7 @@ var SessionMonitor = function(eventWriter) {
  * @param {string} windowId
  * @param {Object} entry
  */
-SessionMonitor.prototype.onEvent = function(windowId, entry) {
+SessionMonitor.prototype.trackSessionStateChanges = function(windowId, entry) {
   var event = /** @type {remoting.ChromotingEvent} */ (base.deepCopy(entry));
 
   if (event.type !== remoting.ChromotingEvent.Type.SESSION_STATE) {

remoting/webapp/crd/js/activation_handler.js

@@ -17,11 +17,12 @@ var NEW_WINDOW_MENU_ID_ = 'new-window';
  *
  * @param {base.Ipc} ipc
  * @param {remoting.V2AppLauncher} appLauncher
+ * @param {remoting.TelemetryEventWriter.Service} telemetryService
  * @extends {base.EventSourceImpl}
  * @implements {base.Disposable}
  * @constructor
  */
-remoting.ActivationHandler = function (ipc, appLauncher) {
+remoting.ActivationHandler = function (ipc, appLauncher, telemetryService) {
   base.inherits(this, base.EventSourceImpl);
   this.defineEvents(base.values(remoting.ActivationHandler.Events));
 
@@ -34,6 +35,9 @@ remoting.ActivationHandler = function (ipc, appLauncher) {
   /** @private {Map<string, base.Disposable>} */
   this.windowClosedHooks_ = new Map();
 
+  /** @private */
+  this.telemetryService_ = telemetryService;
+
   chrome.contextMenus.create({
      id: NEW_WINDOW_MENU_ID_,
      contexts: ['launcher'],
@@ -87,7 +91,7 @@ remoting.ActivationHandler.prototype.onContextMenu_ = function(info) {
  * @private
  */
 remoting.ActivationHandler.prototype.onRestart_ = function(id) {
-  this.appLauncher_.restart(id).then(this.registerCloseListener_.bind(this));
+  this.appLauncher_.restart(id).then(this.onWindowCreated_.bind(this));
 };
 
 /**
@@ -103,16 +107,23 @@ remoting.ActivationHandler.prototype.onLaunched_ = function() {
  * @private
  */
 remoting.ActivationHandler.prototype.createWindow_ = function() {
-  this.appLauncher_.launch().then(this.registerCloseListener_.bind(this));
+  this.appLauncher_.launch().then(this.onWindowCreated_.bind(this));
 };
 
 /**
  * @param {string} windowId
  *
  * @private
  */
-remoting.ActivationHandler.prototype.registerCloseListener_ = function(
+remoting.ActivationHandler.prototype.onWindowCreated_ = function(
     windowId) {
+  // Send the client heartbeat.
+  var event =
+      new remoting.ChromotingEvent(remoting.ChromotingEvent.Type.HEARTBEAT);
+  event.role = remoting.ChromotingEvent.Role.CLIENT;
+  this.telemetryService_.write(''/* No window Id for background page */, event);
+
+  // Register close handler.
   var appWindow = chrome.app.window.get(windowId);
   console.assert(!this.windowClosedHooks_.has(windowId),
                 'Duplicate close listener attached to window : ' + windowId);

remoting/webapp/crd/js/background.js

@@ -42,10 +42,10 @@ BackgroundPage.prototype.preInit_ = function() {
 
   if (base.isAppsV2()) {
     this.appLauncher_ = new remoting.V2AppLauncher();
-    this.activationHandler_ = new remoting.ActivationHandler(
-        base.Ipc.getInstance(), this.appLauncher_);
     this.telemetryService_ = remoting.TelemetryEventWriter.Service.create();
     this.telemetryService_.init();
+    this.activationHandler_ = new remoting.ActivationHandler(
+        base.Ipc.getInstance(), this.appLauncher_, this.telemetryService_);
     this.disposables_.add(new base.EventHook(
         this.activationHandler_, remoting.ActivationHandler.Events.windowClosed,
         this.telemetryService_.unbindSession.bind(this.telemetryService_)));

remoting/webapp/files.gni

@@ -397,6 +397,7 @@ remoting_webapp_background_html_all_js_files += [
   "base/js/oauth2.js",
   "base/js/oauth2_api.js",
   "base/js/oauth2_api_impl.js",
+  "base/js/platform.js",
   "base/js/plugin_settings.js",
   "base/js/telemetry_event_writer.js",
   "base/js/typecheck.js",