Add tests for paint-timing, and move existing tests to same location

third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html

Index: third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html
diff --git a/third_party/WebKit/LayoutTests/fast/performance/performance-paint-timing-observable.html b/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html
similarity index 75%
copy from third_party/WebKit/LayoutTests/fast/performance/performance-paint-timing-observable.html
copy to third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html
index e73b9e6e7e717a4dee0baa41fd4e0744280d91b3..786dc148fb740dfc862482ae231861855e116f51 100644
--- a/third_party/WebKit/LayoutTests/fast/performance/performance-paint-timing-observable.html
+++ b/third_party/WebKit/LayoutTests/http/tests/performance-timing/paint-timing/first-contentful-canvas.html
@@ -6,7 +6,6 @@
     <script src="../../resources/testharness.js"></script>
     <script src="../../resources/testharnessreport.js"></script>
     <script>
-
     async_test(function (t) {
         var observer = new PerformanceObserver(
             t.step_func(function (entryList) {
@@ -28,9 +27,20 @@
         );
         observer.observe({entryTypes: ["paint"]});
 
-    }, "Both first-paint-timing and first-contentful-paint timing entry are observable.");
+    }, "First contentful paint fires due to canvas render.");
+    </script>
 
+    <script>
+      window.onload=function(){

[igrigorik, 2017/05/08 20:37:04]

May be redundant, but perhaps snapshot the time here and make sure that the
startTime of paint entries is greater than onload time?

[panicker, 2017/05/09 17:55:05]

As mentioned let's keep the sequence check in first-contentful-paint.html test

+      var c=document.getElementById("canvas");
+      var ctx=c.getContext("2d");
+      ctx.beginPath();
+      ctx.moveTo(0,0);
+      ctx.lineTo(300,150);
+      ctx.stroke();
+      }
     </script>
-    <div style="background-color:black;color:white;padding:20px;">...test...</div>
+
+    <canvas id="canvas" width="200" height="200" ></canvas>
 </body>
-</html>
+</html>