Update timestmap of file only when content is changed

This can reduce build steps in incremental build.

Bug: 810298
Change-Id: Ie365d765c7bf86a6e8a2bec74c353dcd42a298d1
Reviewed-on: https://chromium-review.googlesource.com/1128675
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573300}
1 file changed