Clean up trace of SigninDiagnosticsObserver in token_service.h/cc. Its usage is removed
in 227510.

BUG=238669

Review URL: https://codereview.chromium.org/64763002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233854 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233854
Make PluginPrefsTest more robust.

Currently PluginPrefsTest.UnifiedPepperFlashState relies on no other
test in unit_tests calling PluginService::GetPlugin(). Doing so causes
the PluginList singleton's loading_state_ to switch to
LOADING_STATE_UP_TO_DATE from LOADING_STATE_NEEDS_REFRESH.
UnifiedPepperFlashState test would then fail due to plugins registered
via RegisterInternalPlugin() not being loaded. This fix adds a
PluginService::RefreshPlugins() call to force the plugins to be loaded
on the next GetPlugin() call.

BUG=316017
BUG=148492

Review URL: https://codereview.chromium.org/64903002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233855 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 233855