Rename GN tool's deps to depsformat. This avoids collisions with the "deps" list of a toolchain. R=noelallen@chromium.org Review URL: https://codereview.chromium.org/361503003 Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src Cr-Mirrored-Commit: c5aba3b3472d3ba4b01b72167caac6b73a82f187