DevTools: fix DevToolsWindow::OpenInNewTab to work in certain cases
DevTools: fix DevToolsWindow::OpenInNewTab to work in certain cases

ATM we don't handle the case of inspected_web_contents->OpenURL method
failing to open url and returning null.

The patch handles this case and tries to open a new tab in existing
browser window, or opens a new browser window if there's none.

BUG=450996
R=dgozman, pfeldman

Review URL: https://codereview.chromium.org/866823002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#312825}

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