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

tools/perf/page_sets/tough_canvas_cases.json

 {
   "description": "Self-driven Canvas2D animation examples",
   "archive_data_file": "data/tough_canvas_cases.json",
   "make_javascript_deterministic": false,
   "smoothness": { "action": "wait", "seconds": 5 },
   "pages": [
     { "url":"http://mudcu.be/labs/JS1k/BreathingGalaxies.html" },
     { "url":"http://runway.countlessprojects.com/prototype/performance_test.html" },
     { "url":"http://geoapis.appspot.com/agdnZW9hcGlzchMLEgtFeGFtcGxlQ29kZRjh1wIM" },
     { "url":"http://ie.microsoft.com/testdrive/Graphics/HowStuffWorksGears/Default.html" },
@@ skipping 11 matching lines @@
     { "url":"http://www.effectgames.com/demos/canvascycle/" },
     { "url":"http://www.thewildernessdowntown.com/" },
     { "url":"http://spielzeugz.de/html5/liquid-particles.html" },
     { "url":"http://hakim.se/experiments/html5/magnetic/02/" },
     { "url":"http://ie.microsoft.com/testdrive/Performance/LetItSnow/" },
     { "url":"http://ie.microsoft.com/testdrive/Graphics/WorkerFountains/Default.html" },
     { "url":"http://ie.microsoft.com/testdrive/Graphics/TweetMap/Default.html" },
     { "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" }
   ]
 }