Refactor prepareToMeasureValuesAsync to startMeasureValuesAsyn which run test through callback

third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js

Index: third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js
diff --git a/third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js b/third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js
index 898e4e845aef1748ec7c40d01afb5d8fe00ade17..66c962e8d0b6ca87d21f22ca47e59e9eec570fbf 100644
--- a/third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js
+++ b/third_party/WebKit/PerformanceTests/Dromaeo/resources/dromaeorunner.js
@@ -8,34 +8,35 @@
                  iterationCount: ITERATION_COUNT,
                  doNotMeasureMemoryUsage: true,
                  doNotIgnoreInitialRun: true,
-                 unit: 'runs/s'
-             });
-
-             var iframe = document.createElement("iframe");
-             var url = DRT.baseURL + "?" + testName + '&numTests=' + ITERATION_COUNT;
-             iframe.setAttribute("src", url);
-             document.body.insertBefore(iframe, document.body.firstChild);
-             iframe.addEventListener(
-                 "load", function() {
-                     DRT.targetDocument = iframe.contentDocument;
-                     DRT.targetWindow = iframe.contentDocument.defaultView;
-                 });
+                 unit: 'runs/s',
+                 run: function() {
+                     var iframe = document.createElement("iframe");
+                     var url = DRT.baseURL + "?" + testName + '&numTests=' + ITERATION_COUNT;
+                     iframe.setAttribute("src", url);
+                     document.body.insertBefore(iframe, document.body.firstChild);
+                     iframe.addEventListener(
+                         "load", function() {
+                             DRT.targetDocument = iframe.contentDocument;
+                             DRT.targetWindow = iframe.contentDocument.defaultView;
+                         });
 
-             window.addEventListener(
-                 "message",
-                 function(event) {
-                     switch(event.data.name) {
-                     case "dromaeo:ready":
-                         DRT.start();
-                         break;
-                     case "dromaeo:progress":
-                         DRT.progress(event.data);
-                         break;
-                     case "dromaeo:alldone":
-                         DRT.teardown(event.data);
-                         break;
-                     }
-                 });
+                     window.addEventListener(
+                         "message",
+                         function(event) {
+                             switch(event.data.name) {
+                             case "dromaeo:ready":
+                                 DRT.start();
+                                 break;
+                             case "dromaeo:progress":
+                                 DRT.progress(event.data);
+                                 break;
+                             case "dromaeo:alldone":
+                                 DRT.teardown(event.data);
+                                 break;
+                             }
+                         });
+                   }
+             });
          },
 
          start: function() {