Add "previewing on hover" support for password field.

components/password_manager/core/browser/password_autofill_manager.h

Index: components/password_manager/core/browser/password_autofill_manager.h
diff --git a/components/password_manager/core/browser/password_autofill_manager.h b/components/password_manager/core/browser/password_autofill_manager.h
index e3f714108ebce4b32fac60b8a8ca85e2af9e0b2f..f72720ee167f17c0abd5b0469e0251472761b713 100644
--- a/components/password_manager/core/browser/password_autofill_manager.h
+++ b/components/password_manager/core/browser/password_autofill_manager.h
@@ -59,6 +59,10 @@ class PasswordAutofillManager : public autofill::AutofillPopupDelegate {
   bool AcceptSuggestionForTest(const autofill::FormFieldData& field,
                                const base::string16& username);
 
+  // A public version of SelectSuggestion(), only for use in tests.
+  bool SelectSuggestionForTest(const autofill::FormFieldData& field,
+                               const base::string16& username);
+
  private:
   typedef std::map<autofill::FormFieldData, autofill::PasswordFormFillData>
       LoginToPasswordInfoMap;
@@ -68,6 +72,11 @@ class PasswordAutofillManager : public autofill::AutofillPopupDelegate {
   bool AcceptSuggestion(const autofill::FormFieldData& field,
                         const base::string16& username);
 
+  // Attempts to preview the password associated with user name |username|, and
+  // returns true if it was successful.
+  bool SelectSuggestion(const autofill::FormFieldData& field,
+                        const base::string16& username);

[Ilya Sherman, 2014/05/13 00:44:05]

nit: Let's name these methods "FillSuggestion" and "PreviewSuggestion".

[ziran.sun, 2014/05/14 15:35:12]

Done.

+
   // If |current_username| matches a username for one of the login mappings in
   // |fill_data|, returns true and assigns the password to |out_password|.
   // Otherwise, returns false and leaves |out_password| untouched.