[Telemetry] Fail fast if Browser goes away during launch

In the case of an error launching Chrome, Telemetry will hang for 30 seconds waiting for Chrome to reply on the socket before it realizes the browser has gone away.

This CL adds a call to .poll() in ChromeBrowserBackend._WaitForBrowserToComeUp() which will throw an exception if Chrome goes away on launch so Telemetry can exit instantly.

BUG=None

Review URL: https://codereview.chromium.org/138663008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249045 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249045
DevTools: Do not call chrome::Navigate from DevToolsWindow, navigate WebContents explicitly instead.

R=pfeldman, dgozman
BUG=336232

Review URL: https://codereview.chromium.org/150343002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249046 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249046
DeclarativeContentApiTest.Overview shouldn't rely on details of layout timing

This CL fixes the DeclarativeContentApiTest.Overview browser_test not to depend
on exact details of when Blink schedules layout. Instead of taking two trips
through the event loop, we just force a synchronous layout.

This CL fixes a bug that will be uncovered once we move layout to be driven off
requestAnimationFrame instead of off a timer.

R=jyasskin@chromium.org
BUG=340357
NOTRY=true

Review URL: https://codereview.chromium.org/154443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249047 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249047