Disable the angular poll channel when the browser tab is hidden

Quay pages that normally poll (repo view, build logs, etc) will skip the API call(s) when the tab is hidden.

static/js/services/angular-poll-channel.js

@@ -1,7 +1,8 @@
 /**
  * Specialized class for conducting an HTTP poll, while properly preventing multiple calls.
  */
-angular.module('quay').factory('AngularPollChannel', ['ApiService', '$timeout', function(ApiService, $timeout) {
+angular.module('quay').factory('AngularPollChannel', ['ApiService', '$timeout', 'DocumentVisibilityService',
+    function(ApiService, $timeout, DocumentVisibilityService) {
   var _PollChannel = function(scope, requester, opt_sleeptime) {
     this.scope_ = scope;
     this.requester_ = requester;
@@ -50,6 +51,12 @@ angular.module('quay').factory('AngularPollChannel', ['ApiService', '$timeout',
   _PollChannel.prototype.call_ = function() {
     if (this.working) { return; }
 
+    // If the document is currently hidden, skip the call.
+    if (DocumentVisibilityService.isHidden()) {
+      this.setupTimer_();
+      return;
+    }
+
     var that = this;
     this.working = true;
     this.scope_.$apply(function() {

static/js/services/document-visibility-service.js

@@ -0,0 +1,60 @@
+/**
+ * Helper service which fires off events when the document's visibility changes, as well as allowing
+ * other Angular code to query the state of the document's visibility directly.
+ */
+angular.module('quay').constant('CORE_EVENT', {
+  DOC_VISIBILITY_CHANGE: 'core.event.doc_visibility_change'
+});
+
+angular.module('quay').factory('DocumentVisibilityService', ['$rootScope', '$document', 'CORE_EVENT',
+    function($rootScope, $document, CORE_EVENT) {
+  var document = $document[0],
+  features,
+  detectedFeature;
+
+  function broadcastChangeEvent() {
+    $rootScope.$broadcast(CORE_EVENT.DOC_VISIBILITY_CHANGE,
+                          document[detectedFeature.propertyName]);
+  }
+
+  features = {
+    standard: {
+      eventName: 'visibilitychange',
+      propertyName: 'hidden'
+    },
+    moz: {
+      eventName: 'mozvisibilitychange',
+      propertyName: 'mozHidden'
+    },
+    ms: {
+      eventName: 'msvisibilitychange',
+      propertyName: 'msHidden'
+    },
+    webkit: {
+      eventName: 'webkitvisibilitychange',
+      propertyName: 'webkitHidden'
+    }
+  };
+
+  Object.keys(features).some(function(feature) {
+    if (document[features[feature].propertyName] !== undefined) {
+      detectedFeature = features[feature];
+      return true;
+    }
+  });
+
+  if (detectedFeature) {
+    $document.on(detectedFeature.eventName, broadcastChangeEvent);
+  }
+
+  return {
+    /**
+     * Is the window currently hidden or not.
+     */
+    isHidden: function() {
+      if (detectedFeature) {
+        return document[detectedFeature.propertyName];
+      }
+    }
+  };
+}]);