Expose method for setting the proxy config in URLRequestContextBuilder for all platforms.

This is so we can bypass the proxy in ChromeDriver (see chrome/test/chromedriver/README).
This is to get around problem many users are having where windows autodetect setting breaks chromedriver.
BUG=chromedriver:310,chromedriver:615

Review URL: https://codereview.chromium.org/68213021

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235875 0039d316-1c4b-4281-b951-d872f2087c98
Fix browser crash when parsing an Settings Override manifest with invalid URLs under 'chrome_settings_overrides.search_provider'.

BUG=

Review URL: https://codereview.chromium.org/71303009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235876 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235876
Introduce RenderProcessHostObserver, use it in its first client.

BUG=170921
TEST=everything still works

Review URL: https://codereview.chromium.org/72203003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@235877 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 235877