Revert 183382

Revert 183382
> Add a ResourceScheduler to ResourceDispatcherHost.
> 
> For this CL, ResourceScheduler mimicks WebKit's ResourceLoadScheduler. That means only JS and CSS are loaded before first paint.
> 
> Eventually, we will improve it to do things like:
> - Lower priority of background tabs.
> - Preconnect for low priority resources.
> - Dynamically adapt scheduling to the user's connection.
> - Experiment with other scheduling ideas.
> 
> BUG=157763
> 
> 
> Review URL: https://chromiumcodereview.appspot.com/11270027

TBR=simonjam@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=183843

[karen, 2013-02-21 18:57:38]

Committed patchset #1 manually as r183843.

[James Simonsen, 2013-02-21 19:01:24]

lgtm