MD Settings: Bluetooth: Clean up observers and discovery logic

chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js

Index: chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js
diff --git a/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js b/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js
index eec93c88966f03604539f1f3f60bfe940e0d67b8..bbff7a444320c4665809a22a8290ce354dec454f 100644
--- a/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js
+++ b/chrome/browser/resources/settings/bluetooth_page/bluetooth_subpage.js
@@ -24,7 +24,6 @@ Polymer({
     /** Reflects the bluetooth-page property. */
     bluetoothEnabled: {
       type: Boolean,
-      observer: 'bluetoothEnabledChanged_',
       notify: true,
     },
 
@@ -148,21 +147,22 @@ Polymer({
 
   /**
    * Listener for chrome.bluetooth.onBluetoothDeviceAdded/Changed events.
-   * @type {function(!chrome.bluetooth.Device)|undefined}
+   * @type {?function(!chrome.bluetooth.Device)}
    * @private
    */
-  bluetoothDeviceUpdatedListener_: undefined,
+  bluetoothDeviceUpdatedListener_: null,
 
   /**
    * Listener for chrome.bluetooth.onBluetoothDeviceRemoved events.
-   * @type {function(!chrome.bluetooth.Device)|undefined}
+   * @type {?function(!chrome.bluetooth.Device)}
    * @private
    */
-  bluetoothDeviceRemovedListener_: undefined,
+  bluetoothDeviceRemovedListener_: null,
 
   /** @override */
   attached: function() {
     this.bluetoothDeviceUpdatedListener_ =
+        this.bluetoothDeviceUpdatedListener_ ||
         this.onBluetoothDeviceUpdated_.bind(this);
     this.bluetooth.onDeviceAdded.addListener(
         this.bluetoothDeviceUpdatedListener_);
@@ -170,6 +170,7 @@ Polymer({
         this.bluetoothDeviceUpdatedListener_);
 
     this.bluetoothDeviceRemovedListener_ =
+        this.bluetoothDeviceRemovedListener_ ||
         this.onBluetoothDeviceRemoved_.bind(this);
     this.bluetooth.onDeviceRemoved.addListener(
         this.bluetoothDeviceRemovedListener_);
@@ -177,16 +178,12 @@ Polymer({
 
   /** @override */
   detached: function() {
-    if (this.bluetoothAdapterStateChangedListener_) {
-      this.bluetooth.onAdapterStateChanged.removeListener(
-          this.bluetoothAdapterStateChangedListener_);
-    }
-    if (this.bluetoothDeviceUpdatedListener_) {
-      this.bluetooth.onDeviceAdded.removeListener(
-          this.bluetoothDeviceUpdatedListener_);
-      this.bluetooth.onDeviceChanged.removeListener(
-          this.bluetoothDeviceUpdatedListener_);
-    }
+    this.bluetooth.onDeviceAdded.removeListener(
+        assert(this.bluetoothDeviceUpdatedListener_));
+    this.bluetooth.onDeviceChanged.removeListener(
+        assert(this.bluetoothDeviceUpdatedListener_));
+    this.bluetooth.onDeviceRemoved.removeListener(
+        assert(this.bluetoothDeviceRemovedListener_));
   },
 
   /**
@@ -195,12 +192,7 @@ Polymer({
    * @protected
    */
   currentRouteChanged: function(route) {
-    if (route == settings.Route.BLUETOOTH_DEVICES) {
-      if (this.bluetoothEnabled)
-        this.startDiscovery_();
-    } else {
-      this.stopDiscovery_();
-    }
+    this.updateDiscovery_();
   },
 
   /** @private */
@@ -210,20 +202,11 @@ Polymer({
 
   /** @private */
   adapterStateChanged_: function() {
+    this.updateDiscovery_();
     this.updateDeviceList_();
   },
 
   /** @private */
-  bluetoothEnabledChanged_: function() {
-    if (settings.getCurrentRoute() == settings.Route.BLUETOOTH_DEVICES &&
-        this.bluetoothEnabled) {
-      this.startDiscovery_();
-    } else {
-      this.stopDiscovery_();
-    }
-  },
-
-  /** @private */
   deviceListChanged_: function() {
     this.saveScroll(this.$.pairedDevices);
     this.saveScroll(this.$.unpairedDevices);
@@ -250,6 +233,16 @@ Polymer({
       this.connectDevice_(this.selectedUnpairedItem_);
   },
 
+  /** @private */
+  updateDiscovery_: function() {
+    if (!this.adapterState || !this.adapterState.powered)
+      return;
+    if (settings.getCurrentRoute() == settings.Route.BLUETOOTH_DEVICES)
+      this.startDiscovery_();
+    else
+      this.stopDiscovery_();
+  },
+
   /**
    * If bluetooth is enabled, request the complete list of devices and update
    * this.deviceList_.