Rename build/config/mac/gen_plist.py to build/config/mac/plist_util.py
after splitting the possible action (currently variable substitution and
plist merging).
Extend tweak_info_plist template to add another parameter info_plists
corresponding to a list of path to merge before tweaking (this allow for
adding partial plist files depending on configuration options).
Always pass the --platform variable based on the value of $current_os
to the tweak_info_plist template and make args optional.
Refactor info_plist template to use separate steps for merge and variable
substitution (as the script now implement them as two separate actions).
BUG=613543
Review-Url: https://codereview.chromium.org/2480433002
Cr-Original-Commit-Position: refs/heads/master@{#429830}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 9bb379e5fbd071abaf1359d724eb79b1ff6e7ceb
sdefresne
rsesek