Collecting LatencyInfo in telemetry

This CL collects input event LatencyInfo from trace buffer and
generates input latency metrics:

mouse_wheel_latency:
From when mouse wheel event reaches RWH to when buffer is swapped.

touch_scroll_latency:
From when the touch event is generated to when the the buffer
is swapped due to the gesture scroll generated from the touch event.

BUG=246034
TEST=telemetry smoothness test on top_25.json works on ChromeOS & Android.

Review URL: https://codereview.chromium.org/132433004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249131 0039d316-1c4b-4281-b951-d872f2087c98
List each privet filesystem on the local network as a single volume

Have each privet filesystem on the local network be its own volume. This logic
is encapsulated in PrivetVolumeLister, which can be swapped out to use cloud
volumes instead of local volumes once we start implementing the cloud API.

BUG=332182

Review URL: https://codereview.chromium.org/134303004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249132 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249131
Add computer model info for ChromeOS in WebRTC logs.

- Logging hardware_class string for ChromeOS.
- LogMachineInfo is split up in two functions. (Network interface part broken out.)
- LogMachineInfo now runs on IO thread. (Getting the string requires that.)

BUG=341000

Review URL: https://codereview.chromium.org/142703012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249133 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249133