Fix order of initialization warning in target_process.cc.

The build was failing with the following Clang error:

..\..\sandbox\win\src\target_process.cc(77,7):
error: field 'initial_token_' will be initialized after field 'lowbox_token_' [-Werror,-Wreorder]
      initial_token_(initial_token.Pass()),
      ^

BUG=82385
TBR=forshaw

Review URL: https://codereview.chromium.org/1408443002 .

Cr-Commit-Position: refs/heads/master@{#353765}
1 file changed