[Password Manager] Add UMA signals to understand how often the password form submit navigate…

components/password_manager/core/browser/password_manager_client.h

Index: components/password_manager/core/browser/password_manager_client.h
diff --git a/components/password_manager/core/browser/password_manager_client.h b/components/password_manager/core/browser/password_manager_client.h
index 43f014d73ec6342bcf1656c7bb3e5dba5ec163ac..9f8c5d92f12e369ec8fe51cbd60ef8073f735d06 100644
--- a/components/password_manager/core/browser/password_manager_client.h
+++ b/components/password_manager/core/browser/password_manager_client.h
@@ -158,6 +158,9 @@ class PasswordManagerClient {
   // Returns the AutofillManager for the main frame.
   virtual autofill::AutofillManager* GetAutofillManagerForMainFrame();
 
+  // Informs the embedder that the password form has been parsed.
+  virtual void OnPasswordFormsParsed() {}
+
  private:
   DISALLOW_COPY_AND_ASSIGN(PasswordManagerClient);
 };