New Profile metric for Auth Errors.

components/signin/core/browser/signin_client.h

Index: components/signin/core/browser/signin_client.h
diff --git a/components/signin/core/browser/signin_client.h b/components/signin/core/browser/signin_client.h
index c8f8a4d2adc2b3d5658fe7c83574056a6f96b4a6..0b9c9324657547bf15686c83ff17c31d9264928c 100644
--- a/components/signin/core/browser/signin_client.h
+++ b/components/signin/core/browser/signin_client.h
@@ -9,6 +9,7 @@
 #include "base/callback_list.h"
 #include "base/time/time.h"
 #include "components/keyed_service/core/keyed_service.h"
+#include "components/signin/core/browser/signin_error_controller.h"
 #include "components/signin/core/browser/webdata/token_web_data.h"
 #include "net/cookies/cookie_store.h"
 #include "url/gurl.h"
@@ -31,7 +32,8 @@ class ProfileOAuth2TokenServiceIOSProvider;
 
 // An interface that needs to be supplied to the Signin component by its
 // embedder.
-class SigninClient : public KeyedService {
+class SigninClient : public KeyedService,
+                     public SigninErrorController::Observer {

[Roger Tawa OOO till Jul 10th, 2015/01/06 22:32:42]

ChromeSigninClient should implement this interface directly instead of
inheriting from SigninClient.  It should then add itself as an observer when
created, instead of being added in the SigninErrorController ctor.

However, I see that this will create a circular PKS dependency chain: PO2TS ->
ChromeSigninClient -> PO2TS.  But it seems we are creating this dependency
anyway; since ChromeSigninClient::OnErrorChanged() calls on PO2TS,
ChromeSigninClientFactory should be updated to depend on PO2TSFactory.

We discussed making SigninErrorController its own PKS, but thought that was a
cleanup for later.  Maybe it should be done here.  Both PO2TS and
ChromeSigninClientFactory can depend on SigninErrorController, and the latter
depends on nothing.

  public:
   // The subcription for cookie changed notifications.
   class CookieChangedSubscription {