[telemetry] Support absolute paths by changing file:/// to file://. More robust file path handling.

tools/perf/page_sets/tough_canvas_cases.json

Index: tools/perf/page_sets/tough_canvas_cases.json
diff --git a/tools/perf/page_sets/tough_canvas_cases.json b/tools/perf/page_sets/tough_canvas_cases.json
index 627c815be09cccf7b8d5b7a870a8774ae0988d76..c51099ddec866afbd1bea0b73aecad644e3e5677 100644
--- a/tools/perf/page_sets/tough_canvas_cases.json
+++ b/tools/perf/page_sets/tough_canvas_cases.json
@@ -29,12 +29,12 @@
     { "url":"http://ie.microsoft.com/testdrive/Graphics/VideoCity/Default.html" },
     { "url":"http://ie.microsoft.com/testdrive/Performance/AsteroidBelt/Default.html" },
     { "url":"http://www.smashcat.org/av/canvas_test/" },
-    { "url": "file:///tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=canvas_sprite&back=canvas" },
-    { "url": "file:///tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=image_with_shadow&back=image" },
-    { "url": "file:///tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=filled_path&back=gradient" },
-    { "url": "file:///tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=text&back=white&ball_count=15" },
-    { "url": "file:///tough_canvas_cases/canvas-animation-no-clear.html" },
-    { "url": "file:///../../../chrome/test/data/perf/canvas_bench/single_image.html" },
-    { "url": "file:///../../../chrome/test/data/perf/canvas_bench/many_images.html" }
+    { "url": "file://tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=canvas_sprite&back=canvas" },
+    { "url": "file://tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=image_with_shadow&back=image" },
+    { "url": "file://tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=filled_path&back=gradient" },
+    { "url": "file://tough_canvas_cases/canvas2d_balls_common/bouncing_balls.html?ball=text&back=white&ball_count=15" },
+    { "url": "file://tough_canvas_cases/canvas-animation-no-clear.html" },
+    { "url": "file://../../../chrome/test/data/perf/canvas_bench/single_image.html" },
+    { "url": "file://../../../chrome/test/data/perf/canvas_bench/many_images.html" }
   ]
 }