Remove unused AccountTracker::Observer methods

As part of the move toward eliminating AccountTracker entirely (see bug),
this CL removes two AccountTracker::Observer methods that are
essentially unused in the codebase (their one production implementation
simply uses them to print logging messages, which could happen just as
easily in AccountTracker itself if needed).

The third method (OnSignInChanged()) is actually used. Eliminating this
method will likely require porting its consumers to observe the
OAuth2TokenService instead.

TBR=rockot@chromium.org

Bug: 729590
Change-Id: I2300f83e8f402ac54783eae212efc8debe598e0b
Reviewed-on: https://chromium-review.googlesource.com/538618
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Nicolas Zea <zea@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#481852}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: f635214c16cc19b3ff5cb4d563ab0c3ce0eae510
3 files changed