Bug 837672 - Add events to track camera startup performance

apps/camera/index.html

@@ -12,6 +12,9 @@
     <link rel="stylesheet" type="text/css" href="shared/style/buttons.css">
 
     <script defer src="/shared/js/l10n.js"></script>
+    <!-- for perf-measurement related utilities -->
+    <script defer src="/shared/js/performance_testing_helper.js"></script>
+
     <!-- The following scripts are lazy loaded but left here to ensure
          they get copied over from shared during the build -->
     <!-- <script defer src="/shared/js/async_storage.js"></script> -->

apps/camera/js/camera.js

@@ -253,7 +253,9 @@ var Camera = {
   init: function() {
     var self = this;
     this.setCaptureMode(this.CAMERA);
+    PerformanceTestingHelper.dispatch('initialising-camera-preview');
     this.loadCameraPreview(this._camera, function() {
+      PerformanceTestingHelper.dispatch('camera-preview-loaded');
       var files = [
         'style/filmstrip.css',
         'style/VideoPlayer.css',
@@ -360,6 +362,7 @@ var Camera = {
 
     this.previewEnabled();
     DCFApi.init();
+    PerformanceTestingHelper.dispatch('startup-path-done');
   },
 
   screenTimeout: function camera_screenTimeout() {