Disable timing from chrome://profiler on Android.

On Android, on a arm CPU, TimeTicks::Now() is taking 900ns (20 times
what it takes on a desktop x86 CPU). The bigger user of TimeTicks::Now()
is tracked_objects::TrackedTime, and this impacts the overall
performance of Chrome on this platform.

This CL adds compile line flags that allows to disable
tracked_objects::TrackedTime. It also disable
tracked_objects::TrackedTime by default on Android.

BUG=315070

Review URL: https://codereview.chromium.org/99343002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240092 0039d316-1c4b-4281-b951-d872f2087c98
DevTools: Delay updates in chrome://inspect#pages

chrome://inspect relies on NOTIFICATION_WEB_CONTENTS_DESTROYED to update
the pages list when the tab is being closed. Sometimes the notification
arrives while the page is still alive. This patch delays the page list
update. Repetitive updates are coalesced.

BUG=327274

Review URL: https://codereview.chromium.org/101223004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240093 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240093