Add rasterization microbenchmark for silk

Add rasterize_and_record_micro_key_silk_cases for keeping track of
rasterization and recording performance of silk content. This mirrors
the existing rasterize_and_record_key_silk_cases benchmark and will
potentially allow us to remove it if this microbenchmark produces less
noisy data.

BUG=339517

Review URL: https://codereview.chromium.org/177253003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253403 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253403
Pepper: Add channel for trusted plugin.

As part of converting trusted plugin communication from SRPC to Chromium IPC,
we need to add a channel for this communication to happen over. LaunchSelLdr()
is a natural place for this to be.

BUG=333950

Review URL: https://codereview.chromium.org/157803011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253404 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253404