Make HttpAuthHandler ctor public/@hide.
Make HttpAuthHandler ctor public/@hide.

The Chromium WebView Provider needs to subclass HttpAuthHandler
so that we can adapt a ChromHttpAuthHandler into an
android.webkit.HttpAuthHandler. Currently the constructor (that
does nothing) is package private. So to satisfy the subclass
requirement, make it public, and to satisfy the API, make it
@hide.

Bug: 7034995
Change-Id: I9846aecacce078696db5be709394afb980eb25a6

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base