Track when and how a profile is signed out via UMA.

chrome/browser/android/signin/signin_manager_android.cc

Index: chrome/browser/android/signin/signin_manager_android.cc
diff --git a/chrome/browser/android/signin/signin_manager_android.cc b/chrome/browser/android/signin/signin_manager_android.cc
index 37cd951f34e58577f0e80abcd97b9366eb280ce0..a968ed8202840528d34356fb809d57f90c8b9880 100644
--- a/chrome/browser/android/signin/signin_manager_android.cc
+++ b/chrome/browser/android/signin/signin_manager_android.cc
@@ -23,6 +23,7 @@
 #include "components/bookmarks/browser/bookmark_model.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_manager.h"
+#include "components/signin/core/browser/signin_metrics.h"
 #include "components/signin/core/common/profile_management_switches.h"
 #include "jni/SigninManager_jni.h"
 
@@ -133,6 +134,7 @@ void SigninManagerAndroid::OnSignInCompleted(JNIEnv* env,
 }
 
 void SigninManagerAndroid::SignOut(JNIEnv* env, jobject obj) {
+  signin_metrics::LogSignout(signin_metrics::USER_CLICKED_SIGNOUT);
   SigninManagerFactory::GetForProfile(profile_)->SignOut();
 }