Allows gtk2 printing dialog in Linux-Aura.

A todo is the parent/dialog relationship. Right now print_dialog_gtk2
creates the dialog with NULL parent, so the dialog can move under the
browser window.

We need to do something similar to select_file_dialog_impl_gtk2.cc

BUG=317882
R=erg@chromium.org, thestig@chromium.org, vitalybuka@chromium.org
TEST=manually

Review URL: https://codereview.chromium.org/135163003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244734 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244734
Update webrtc browsetest to use TraceAnalyzer instead of trying to parse the JSON event structure itself.

Review URL: https://codereview.chromium.org/117443004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244735 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 244735