Add important_file_writer_unittest.cc to Windows build.
Add important_file_writer_unittest.cc to Windows build.

I forgot that unittests.vcproj is not gypified...

TEST=There should be at least one test in unit_tests matching ImportantFileWriterTest.* on Windows

http://crbug.com/10618

Review URL: http://codereview.chromium.org/115077

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@15539 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser