HAR: export only finished requests.
HAR: export only finished requests.

BUG=350113
NOTRY=true

Review URL: https://codereview.chromium.org/197193002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@169089 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs