[Devtools] Added simplified/latency view to network timeline experiment

This patch introduces the colorized timeline view to network panel
timeline. This can currently be reached by turning on "Color-code
resource types" in settings.

See: http://imgur.com/a/MOInX

R=dgozman
BUG=653738

Review-Url: https://chromiumcodereview.appspot.com/2418953002
Cr-Commit-Position: refs/heads/master@{#426551}

third_party/WebKit/Source/devtools/front_end/network/networkLogView.css

@@ -377,7 +377,7 @@
 }
 
 /* Resource categories */
-
+/* TODO(allada) Remove these when we remove canvas timeline experiment */
 .network-graph-bar.request-timing.queueing,
 .network-graph-bar.request-timing.total,
 .network-graph-bar.request-timing.proxy,