Revert "[ChromeDriver] Use Browser.close to quit"

This reverts commit 3edba584fc9d669b16f26a6516dc080197144485.

Reason for revert: Code not working properly on Mac

Original change's description:
> [ChromeDriver] Use Browser.close to quit
> 
> Currently, ChromeDriver closes desktop Chrome by simply killing the
> top-level Chrome process. This isn't graceful, and causes problems
> in some scenarios. This commit sends a Browser.close command to close
> the browser gracefully.
> 
> Bug: chromedriver:2311
> Change-Id: Idec9338b094f0aab89022b8453dd2a98268ad1e7
> Reviewed-on: https://chromium-review.googlesource.com/1037585
> Commit-Queue: John Chen <johnchen@chromium.org>
> Reviewed-by: Jonathon Kereliuk <kereliuk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#556689}

TBR=johnchen@chromium.org,kereliuk@chromium.org

Change-Id: I53f310a7745586fdcbebb1edd58b5eb0d7873475
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromedriver:2311
Reviewed-on: https://chromium-review.googlesource.com/1049146
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556708}
1 file changed