Files.app: Add a general sync error message.

Previously Files.app did not show sync error messages other than for the
specific error. This CL adds a general sync error message for the other errors.

BUG=335454
TEST=show the message by running out of the space of the drive.

Review URL: https://codereview.chromium.org/143843002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246296 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246296
Bug fix: add width attribute to .content-area

Added a constant value to .content-area and changed the width of #language-options-details (the right panel) flexible.

BUG=336300
TEST=manual

Review URL: https://codereview.chromium.org/143873002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246297 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246297