Move DownloadDirPolicyHandler to live in chrome/browser/download.

This facilitates the refactoring of chrome/browser/policy into a layered
component.

BUG=271392

Review URL: https://codereview.chromium.org/27197015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229797 0039d316-1c4b-4281-b951-d872f2087c98
[android_webview] Fix crash in testCreateDestroy.

The onSizeChanged callback was arriving after the AwContents was destroyed.
Ignoring the setFixedLayoutSize call is fine since the AwContents is going
away anyway.

BUG=308497
R=mnaganov@chromium.org

Review URL: https://codereview.chromium.org/28923005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229798 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229798