Revert of Telemetry: Initialize smoothness and thread_times metrics before page load, not after.

Revert of Telemetry: Initialize smoothness and thread_times metrics before page load, not after. (https://codereview.chromium.org/392613002/)

Reason for revert:
Breaks smoothness tests on N4 (at least) with no frames error. Possible this is a legit perf regression? But reverting anyway to green things up.

http://build.chromium.org/p/chromium.perf/builders/Android%20Nexus5%20Perf/builds/1115

Original issue's description:
> Telemetry: Initialize smoothness and thread_times metrics before page load, not after.
> 
> Currently both smoothness and thread_times initialize their metrics after page
> load. This leads to a gap between the page load and the page actions starting.
> This patch moves the initialization before the page load, thus eliminating the
> gap. It is safe to do so because smoothness and thread_times require a page load
> before each run (even when repeating the same page).
> 
> Note to perf sheriffs:
> This patch is likely to cause performance numbers to worsen, because the browser is often more busy immediately after page load. If you get alerts related to this CL, feel free to ignore them. If there is a reference build for the bot, the number for the reference build should also change accordingly.
> 
> BUG=392895
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285297

TBR=skyostil@chromium.org,picksi@google.com,dominikg@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=392895
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=285395

[tonyg, 2014-07-24 22:34:53]

Created Revert of Telemetry: Initialize smoothness and thread_times metrics
before page load, not after.

[commit-bot: I haz the power, 2014-07-24 22:36:01]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tonyg@chromium.org/419623002/1

[commit-bot: I haz the power, 2014-07-24 22:38:34]

Change committed as 285395