Add a11y virtual keyboard icon when a11y VK is enabled

This CL adds a virtual keyboard icon when a11y VK is enabled. Click or tap on
the icon will force the VK to show and lock.

BUG=346695

Review URL: https://codereview.chromium.org/177123016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255307 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255307
Remove unused variable in MediaDrmCredentialManager.java

R=tedchoc@chromium.org

Review URL: https://codereview.chromium.org/185223002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255308 0039d316-1c4b-4281-b951-d872f2087c98
Remove unconditionally set "--no-proxy-server" browser flag.

BUG=349589

Review URL: https://codereview.chromium.org/188023003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255309 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255308
SVN changes up to revision 255309