Log some very basic timers in WebUI tests using PolymerTest

chrome/test/data/webui/polymer_browser_test_base.js

Index: chrome/test/data/webui/polymer_browser_test_base.js
diff --git a/chrome/test/data/webui/polymer_browser_test_base.js b/chrome/test/data/webui/polymer_browser_test_base.js
index d79ce512b84c0e907061f7caa1b5aa90dfb2815e..5c127b66cf7c23d78f98aa80ff5f2ba1b50ebe66 100644
--- a/chrome/test/data/webui/polymer_browser_test_base.js
+++ b/chrome/test/data/webui/polymer_browser_test_base.js
@@ -42,8 +42,24 @@ PolymerTest.prototype = {
     'chrome/test/data/webui/mocha_adapter.js',
   ],
 
+  /** Time when preLoad starts, i.e. before the browsePreload page is loaded. */
+  preloadTime: 0,
+
+  /** Time when test setup starts. */
+  setupTime: 0,
+
+  /** Time when test run starts. */
+  runTime: 0,
+
+  /** @override */
+  preLoad: function() {
+    this.preloadTime = window.performance.now();
+    testing.Test.prototype.preLoad.call(this);
+  },
+
   /** @override */
   setUp: function() {
+    this.setupTime = window.performance.now();
     testing.Test.prototype.setUp.call(this);
 
     // List of imported URLs for debugging purposes.
@@ -90,6 +106,24 @@ PolymerTest.prototype = {
       return Promise.all(promises);
     });
   },
+
+  /** @override */
+  runTest: function(testBody) {
+    this.runTime = window.performance.now();
+    testing.Test.prototype.runTest.call(this, testBody);
+  },
+
+  /** @override */
+  tearDown: function() {
+    var endTime = window.performance.now();
+    var delta = this.setupTime - this.preloadTime;
+    console.log('Page load time: ' + delta + " ms");

[michaelpg, 2015/11/24 23:26:19]

Turns out floats are really annoying to read...

Could we round delta? or if we want to keep decimal places for some reason,
Math.round(delta * 100) / 100

+    delta = endTime - this.runTime;
+    console.log('Test run time: ' + delta + " ms");
+    delta = endTime - this.preloadTime;
+    console.log('Total time: ' + delta + " ms");
+    testing.Test.prototype.tearDown.call(this);

[Dan Beam, 2015/11/23 23:10:51]

nit: can we use console.time() + console.timeEnd()?

[stevenjb, 2015/11/23 23:24:41]

I was thinking that later we might want to do something in individual tests that
log something like 'Time to basic page ready', etc.

Also, I prefer to log all of the times at the end. With console.time I would
need to log, e.g. the page load time before running the tests, making that
output harder to find.

+  }
 };
 
 /**