cc: Clean up LayerTreeHostImplTest init and add check for lost context

I wanted to add a DCHECK() that we call
LayerTreeHostImpl::DidLoseOutputSurface always before destroying
and recreating the ResourceProvider etc.

This failed not on any context loss tests, but rather on a bunch
of LayerTreeHostImplTests (mostly) that were re-initializing the
renderer by hand.

So, instead of having these tests poke the LayerTreeHostImpl in
a weird way, I cleaned up the way the tests create and initialize
the LayerTreeHostImpl.

Test-only change, no new tests.

R=enne, jamesr
BUG=313790

Review URL: https://codereview.chromium.org/93183002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237739 0039d316-1c4b-4281-b951-d872f2087c98
Exclude non-renderer memory from 'Renderer' in Telemetry memory metrics.

It's the first step to stop summing-up RSS (Resident Set Size) of multiple
processes. See the bug for details. A memory-measuring test picks up only one
process when the test has only one renderer. It's a common case in performance
tests though not all.

BUG=323494
NOTRY=True

Review URL: https://codereview.chromium.org/93713002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237740 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237739
SVN changes up to revision 237740