Fix log spew caused by DeleteBranch constructor

Every time branches are accessed the server logs a nasty Guice
trace preventing DeleteBranch from being created. The view must
create without enforcing the IdentifiedUser to exist. The solution
throughout the rest of Gerrit REST API code is to use Provider<X>
instead of X to allow Guice to defer this resolution.

Change-Id: If7fd7f4c38bcbc685d4f9451479da7a9ed432564
1 file changed