DevTools: HAR export: add custom transfer size response field.

This will be useful for developers who use SPDY, as headerSize and bodySize
are unknown in that case.

BUG=444587

Review URL: https://codereview.chromium.org/825243002

git-svn-id: svn://svn.chromium.org/blink/trunk@187768 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: NetworkPanel: show full request lifespan.

BUG=445346

Review URL: https://codereview.chromium.org/833463002

git-svn-id: svn://svn.chromium.org/blink/trunk@187770 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Devtools Animations: Add user metric action for AnimationsPlaybackRateChanged

BUG=432368

Review URL: https://codereview.chromium.org/825563002

git-svn-id: svn://svn.chromium.org/blink/trunk@187776 bbb929c8-8fbe-4397-9dbb-9b2b20218538
DevTools: Improve Promise pane UI.

BUG=442724
R=pfeldman, eustas

Review URL: https://codereview.chromium.org/792213004

git-svn-id: svn://svn.chromium.org/blink/trunk@187778 bbb929c8-8fbe-4397-9dbb-9b2b20218538