[chromedriver] Use mock keychain when launching Chrome subprocess for RemoteBrowserTest.
[chromedriver] Use mock keychain when launching Chrome subprocess for RemoteBrowserTest.

On recent Chromium builds for Mac, it will attempt to access the user's keychain, which throws up a dialog asking the user for permission to access the keychain. If the dialog is not manually dismissed, the RemoteBrowserTest.testConnectToRemoteBrowser test times out.

BUG=
TBR=stgao@chromium.org

Review URL: https://codereview.chromium.org/1012343002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#321034}

Fireblend/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,axinging/chromium-crosswalk,Chilledheart/chromium,PeterWangIntel/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,chuan9/chromium-crosswalk,hgl888/chromium-crosswalk,fujunwei/chromium-crosswalk,ltilve/chromium,hgl888/chromium-crosswalk,axinging/chromium-crosswalk,ltilve/chromium,TheTypoMaster/chromium-crosswalk,ltilve/chromium,axinging/chromium-crosswalk,chuan9/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,chuan9/chromium-crosswalk,ltilve/chromium,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,hgl888/chromium-crosswalk,Chilledheart/chromium,Chilledheart/chromium,TheTypoMaster/chromium-crosswalk,chuan9/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk,chuan9/chromium-crosswalk,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Chilledheart/chromium,ltilve/chromium,Just-D/chromium-1,Just-D/chromium-1,Fireblend/chromium-crosswalk,Chilledheart/chromium,fujunwei/chromium-crosswalk,ltilve/chromium,axinging/chromium-crosswalk,Fireblend/chromium-crosswalk,ltilve/chromium,ltilve/chromium,Pluto-tv/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,fujunwei/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,PeterWangIntel/chromium-crosswalk,fujunwei/chromium-crosswalk,Just-D/chromium-1,Chilledheart/chromium,TheTypoMaster/chromium-crosswalk,fujunwei/chromium-crosswalk,Pluto-tv/chromium-crosswalk,hgl888/chromium-crosswalk,fujunwei/chromium-crosswalk,fujunwei/chromium-crosswalk,Just-D/chromium-1,hgl888/chromium-crosswalk,Pluto-tv/chromium-crosswalk,TheTypoMaster/chromium-crosswalk,Fireblend/chromium-crosswalk,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Fireblend/chromium-crosswalk,hgl888/chromium-crosswalk,Just-D/chromium-1,ltilve/chromium,Just-D/chromium-1,TheTypoMaster/chromium-crosswalk,chuan9/chromium-crosswalk,Chilledheart/chromium,Fireblend/chromium-crosswalk,PeterWangIntel/chromium-crosswalk,Pluto-tv/chromium-crosswalk