Revert 253184 "[Telemetry] Suppress modal dialogs."

> [Telemetry] Suppress modal dialogs.
> 
> This is necessary to run through the top 1000 mobile sites page set completely.
> 
> BUG=
> NOTRY=True
> 
> Review URL: https://codereview.chromium.org/172873009

TBR=tonyg@chromium.org

Review URL: https://codereview.chromium.org/180183002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253209 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253209
Disable mojo tests on chromium_trybot, they are broken on Mac

TBR=darin

BUG=346766, 332239

Review URL: https://codereview.chromium.org/180193002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253210 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253210