Revert 232959 "[Telemetry] Fix image_decoding_measurement timeout."

(Likely) caused timeouts in webgl_conformance_tests on Win and Mac Debug GPU bots.
See Issue 314375 for more details.

> [Telemetry] Fix image_decoding_measurement timeout.
> 
> util.WaitFor polls which is not appropriate for PerformActionAndWaitForNavigate.
> 
> Since DispatchNotifications blocks in recv until it gets some data, there is no
> need to poll at an interval. Instead, we should call recv again as soon as
> possible after dispatching a notification.
> 
> In the case of the image decoding measurement, it runs timeline recording. There
> were so many timeline messages to receive that we were not always getting to the
> important Page.navigate message before timing out.
> 
> Example:
> http://build.chromium.org/p/chromium.perf/builders/Linux%20Perf%20%281%29/builds/27098
> 
> BUG=314375
> 
> Review URL: https://codereview.chromium.org/47013004

TBR=tonyg@chromium.org

Review URL: https://codereview.chromium.org/60233004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233021 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233021