mac: Add WebGL power test

tools/perf/page_sets/trivial_sites/trivial_webgl.html

Index: tools/perf/page_sets/trivial_sites/trivial_webgl.html
diff --git a/tools/perf/page_sets/trivial_sites/trivial_canvas.html b/tools/perf/page_sets/trivial_sites/trivial_webgl.html
similarity index 77%
copy from tools/perf/page_sets/trivial_sites/trivial_canvas.html
copy to tools/perf/page_sets/trivial_sites/trivial_webgl.html
index 567193796aeae1d75dea787512b589330a631fd3..cbfbe384a65f3cc939c26d875ade6b9e869abfb8 100644
--- a/tools/perf/page_sets/trivial_sites/trivial_canvas.html
+++ b/tools/perf/page_sets/trivial_sites/trivial_webgl.html
@@ -22,14 +22,14 @@ found in the LICENSE file.
   canvas.style.height='100%';
   canvas.width  = canvas.offsetWidth;
   canvas.height = canvas.offsetHeight;
-  var ctx = canvas.getContext("2d");
+  var gl = canvas.getContext("webgl");
+  gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
   var rColor = 0;
 
   function animate() {
-    rColor += 1;
-    rColor %= 255;
-    ctx.fillStyle = 'rgb(' + rColor + ',0,0)';
-    ctx.fillRect(0, 0, canvas.width, canvas.height);
+    rColor = (rColor + 1) % 255;
+    gl.clearColor(rColor / 255, 0.0, 0.0, 1.0);
+    gl.clear(gl.COLOR_BUFFER_BIT);
     window.requestAnimationFrame(animate);
   }
   window.onload = animate;