Moving common_export.h to blink's public folder

common_export.h was kept out of public since it was not to be
directly included by users of blink's public API but that made
dependency tracking unnecessarily complicated and it was included
indirectly anyway since many public headers included it.

This patch moves the header to blink's public/common. It's still
not to be include by external blink API users, but there is also
no reason for them to do it. This allows us to remove the dependency
hacks and makes dependency checks easier.

Bug: 800764

Change-Id: I834f389f9c1871a5e1e66b2fa69477b7eb40e0a0
Reviewed-on: https://chromium-review.googlesource.com/c/1301467
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603654}
47 files changed