Migrate fullPaths to URLs in appState.

This patch replaces currentDirectoryPath with currentDirectoryURL, and same for the selectionPath. As a result, the entire appState does not depend on paths anymore.

TEST=browser_tests, also tested manually.
BUG=333168

Review URL: https://codereview.chromium.org/132453007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247855 0039d316-1c4b-4281-b951-d872f2087c98
Fix crash in NativeThemeWin::PaintIndirect when HDC allocation fails

BUG=339117

Review URL: https://codereview.chromium.org/137383007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247856 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247856