Files.app: Replace the message string of new progress center.

Previously the message string of new progress center is embedded in the source
code directly. This CL let the new progress center to use the localized strings.

BUG=277432
R=mtomasz@chromium.org, yoshiki@chromium.org

Review URL: https://codereview.chromium.org/27298003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229074 0039d316-1c4b-4281-b951-d872f2087c98
Disable BrowserPluginHostTest.EmbedderSameAfterNav on Windows.

Failing flakily.

Build log: http://build.chromium.org/p/chromium.win/builders/Vista%20Tests%20%281%29/builds/41250
Flakiness dashboard: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Chromium&testType=content_browsertests&tests=BrowserPluginHostTest.EmbedderSameAfterNav

BUG=308405
TBR=fsamuel

Review URL: https://codereview.chromium.org/26804007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229075 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229075