Fix for caller of GetTmpDir.

Since I changed GetTmpDir to create an SkString each time, it
needs to be assigned to a variable in order for it to stick around.
Update a test which I missed because my client was out of date.

Review URL: https://codereview.chromium.org/15719006

git-svn-id: http://skia.googlecode.com/svn/trunk@9475 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed