[jumbo] Declare a template specialization before using it

A quirk in C++ is that you can't specialize a template after it
has been "used" unspecialized in a translation unit. This would
happen in jumbo builds with
ApiResourceManager<EasyUnlockPrivateConnection>::GetFactoryInstance()
which is defined in easy_unlock_private_connection.cc but used
undeclared in easy_unlock_private_api.cc.

The fix is simple, just declare the specialization before it's used
and this patch adds that declaration to
easy_unlock_private_connection.h.

Bug: 850484
Change-Id: If5c12b67c92889a5c986b6a571d9895dea03cb6e
Reviewed-on: https://chromium-review.googlesource.com/1149860
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#578061}
2 files changed