[Mac/Linux] clean up the shmem file at the end of each testshell run. - Mac/Linux back shmem with a file, but the file isn't cleaned up (since it could be shared), this pulls over the same basic code we used in chrome_test_suite to clean up the files there also so they don't leak a fill up the bots.
[Mac/Linux] clean up the shmem file at the end of each testshell run.
- Mac/Linux back shmem with a file, but the file isn't cleaned up (since it could be shared), this pulls over the same basic code we used in chrome_test_suite to clean up the files there also so they don't leak a fill up the bots.

BUG=32391
TEST=nothing, http://crbug.com/36261 prevents this from really cleaning up resource leaks
Review URL: http://codereview.chromium.org/651038

git-svn-id: http://src.chromium.org/svn/trunk/src@39463 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 0e878bedb7a41ae8e17e978e9406621d801d04bd
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser