GN proto_libary refactoring.

Added support for sub-directories.
Builds multi-file libraries in a single pass to avoid repeated
proto parsing and to follow dependencies strictier.

BUG=637292

Review-Url: https://codereview.chromium.org/2239383002
Cr-Original-Commit-Position: refs/heads/master@{#412970}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: b72583a75181ba099159ce89b3f751054181fa62
1 file changed
tree: 3f2c769e12d464cabfd707be69c5e2489d0058c8
  1. protoc_wrapper.py