Implement Password Manager aggregate metrics reporting

chrome/browser/password_manager/login_database.h

Index: chrome/browser/password_manager/login_database.h
diff --git a/chrome/browser/password_manager/login_database.h b/chrome/browser/password_manager/login_database.h
index 913fc1700e9e2a7ddfbec895efa3a6ab0ba050b0..44b868b1e654760b6809c19122f90faa744b69ab 100644
--- a/chrome/browser/password_manager/login_database.h
+++ b/chrome/browser/password_manager/login_database.h
@@ -28,6 +28,9 @@ class LoginDatabase {
   // If false is returned, no other method should be called.
   bool Init(const FilePath& db_path);
 
+  // Reports usage metrics to UMA.
+  void ReportMetrics();
+
   // Adds |form| to the list of remembered password forms.
   bool AddLogin(const webkit_glue::PasswordForm& form);