Support hotwording on google.com and the new tab page.

chrome/browser/resources/hotword/state_manager.js

Index: chrome/browser/resources/hotword/state_manager.js
diff --git a/chrome/browser/resources/hotword/state_manager.js b/chrome/browser/resources/hotword/state_manager.js
index 39e176b278571580e1788d7458b88931c38ac542..81331e337f2ecae6eb91c84d088281367e73e3c2 100644
--- a/chrome/browser/resources/hotword/state_manager.js
+++ b/chrome/browser/resources/hotword/state_manager.js
@@ -6,6 +6,38 @@ cr.define('hotword', function() {
   'use strict';
 
   /**
+   * Trivial container class for session information.
+   * @param {!hotword.constants.SessionSource} source Source of the hotword
+   *     session.
+   * @param {!function()} triggerCb Callback invoked when the hotword has
+   *     triggered.
+   * @param {!function()} startedCb Callback invoked when the session has
+   *     been started successfully.
+   * @constructor
+   * @struct
+   * @private
+   */
+  function Session_(source, triggerCb, startedCb) {
+    /**
+     * Source of the hotword session request.
+     * @private {!hotword.constants.SessionSource}
+     */
+    this.source_ = source;
+
+     /**
+      * Callback invoked when the hotword has triggered.
+      * @private {!function()}
+      */
+    this.triggerCb_ = triggerCb;
+
+    /**
+     * Callback invoked when the session has been started successfully.
+     * @private {?function()}
+     */
+    this.startedCb_ = startedCb;
+  }
+
+  /**
    * Class to manage hotwording state. Starts/stops the hotword detector based
    * on user settings, session requests, and any other factors that play into
    * whether or not hotwording should be running.
@@ -32,16 +64,16 @@ cr.define('hotword', function() {
     this.pluginManager_ = null;
 
     /**
-     * Source of the current hotword session.
-     * @private {?hotword.constants.SessionSource}
+     * Currently active hotwording sessions.
+     * @private {!Array.<hotword.Session_>}
      */
-    this.sessionSource_ = null;
+    this.sessions_ = [];
 
     /**
-     * Callback to run when the hotword detector has successfully started.
-     * @private {!function()}
+     * Event that fires when the hotwording status has changed.
+     * @type {!chrome.Event}
      */
-    this.sessionStartedCb_ = null;
+    this.onStatusChanged = new chrome.Event();
 
     /**
      * Hotword trigger audio notification... a.k.a The Chime (tm).
@@ -80,6 +112,23 @@ cr.define('hotword', function() {
     },
 
     /**
+     * @return {boolean} True if hotwording is enabled.
+     */
+    isEnabled: function() {
+      assert(this.hotwordStatus_);
+      return this.hotwordStatus_.enabled;
+    },
+
+    /**
+     * @return {boolean} True if always-on hotwording is enabled.
+     */
+    isAlwaysOnEnabled: function() {
+      assert(this.hotwordStatus_);
+      return this.hotwordStatus_.enabled &&
+          this.hotwordStatus_.alwaysOnEnabled;
+    },
+
+    /**
      * Callback for hotwordPrivate.getStatus() function.
      * @param {chrome.hotwordPrivate.StatusDetails} status Current hotword
      *     status.
@@ -89,6 +138,8 @@ cr.define('hotword', function() {
       hotword.debug('New hotword status', status);
       this.hotwordStatus_ = status;
       this.updateStateFromStatus_();
+
+      this.onStatusChanged.dispatch();
     },
 
     /**
@@ -102,17 +153,12 @@ cr.define('hotword', function() {
       if (this.hotwordStatus_.enabled) {
         // Start the detector if there's a session, and shut it down if there
         // isn't.
-        // TODO(amistry): Support stacking sessions. This can happen when the
-        // user opens google.com or the NTP, then opens the launcher. Opening
-        // google.com will create one session, and opening the launcher will
-        // create the second. Closing the launcher should re-activate the
-        // google.com session.
         // NOTE(amistry): With always-on, we want a different behaviour with
         // sessions since the detector should always be running. The exception
         // being when the user triggers by saying 'Ok Google'. In that case, the
         // detector stops, so starting/stopping the launcher session should
         // restart the detector.
-        if (this.sessionSource_)
+        if (this.sessions_.length)
           this.startDetector_();
         else
           this.shutdownDetector_();
@@ -180,9 +226,12 @@ cr.define('hotword', function() {
         this.state_ = State_.RUNNING;
         this.pluginManager_.startRecognizer();
       }
-      if (this.sessionStartedCb_) {
-        this.sessionStartedCb_();
-        this.sessionStartedCb_ = null;
+      for (var i = 0; i < this.sessions_.length; i++) {
+        var session = this.sessions_[i];
+        if (session.startedCb_) {
+          session.startedCb_();
+          session.startedCb_ = null;
+        }
       }
     },
 
@@ -243,12 +292,28 @@ cr.define('hotword', function() {
       // Play the chime.
       this.chime_.play();
 
-      chrome.hotwordPrivate.notifyHotwordRecognition('search', function() {});
+      // Implicitly clear the top session. A session needs to be started in
+      // order to restart the detector.
+      if (this.sessions_.length) {
+        var session = this.sessions_.pop();
+        if (session.triggerCb_)
+          session.triggerCb_();
+      }
+    },
 
-      // Implicitly clear the session. A session needs to be started in order to
-      // restart the detector.
-      this.sessionSource_ = null;
-      this.sessionStartedCb_ = null;
+    /**
+     * Remove a hotwording session from the given source.
+     * @param {!hotword.constants.SessionSource} source Source of the hotword
+     *     session request.
+     * @private
+     */
+    removeSession_: function(source) {
+      for (var i = 0; i < this.sessions_.length; i++) {
+        if (this.sessions_[i].source_ == source) {
+          this.sessions_.splice(i, 1);
+          break;
+        }
+      }
     },
 
     /**
@@ -257,11 +322,13 @@ cr.define('hotword', function() {
      *     session request.
      * @param {!function()} startedCb Callback invoked when the session has
      *     been started successfully.
+     * @param {!function()} triggerCb Callback invoked when the hotword has
+     *     triggered.
      */
-    startSession: function(source, startedCb) {
+    startSession: function(source, startedCb, triggerCb) {
       hotword.debug('Starting session for source: ' + source);
-      this.sessionSource_ = source;
-      this.sessionStartedCb_ = startedCb;
+      this.removeSession_(source);
+      this.sessions_.push(new Session_(source, triggerCb, startedCb));
       this.updateStateFromStatus_();
     },
 
@@ -272,8 +339,7 @@ cr.define('hotword', function() {
      */
     stopSession: function(source) {
       hotword.debug('Stopping session for source: ' + source);
-      this.sessionSource_ = null;
-      this.sessionStartedCb_ = null;
+      this.removeSession_(source);
       this.updateStateFromStatus_();
     }
   };