Implement the chrome.passwordsPrivate API.

chrome/browser/extensions/api/passwords_private/passwords_private_api.h

Index: chrome/browser/extensions/api/passwords_private/passwords_private_api.h
diff --git a/chrome/browser/extensions/api/passwords_private/passwords_private_api.h b/chrome/browser/extensions/api/passwords_private/passwords_private_api.h
index 4cef1917f65877cd7aac77e2b9afeac96a7b7e94..2380b58996fa076fd1c506d6b6de489cda69f8e7 100644
--- a/chrome/browser/extensions/api/passwords_private/passwords_private_api.h
+++ b/chrome/browser/extensions/api/passwords_private/passwords_private_api.h
@@ -8,6 +8,8 @@
 #include <string>
 
 #include "base/macros.h"
+#include "chrome/browser/extensions/api/passwords_private/passwords_private_delegate.h"
+#include "chrome/browser/ui/passwords/password_manager_presenter.h"
 #include "extensions/browser/extension_function.h"
 
 namespace extensions {
@@ -66,8 +68,8 @@ class PasswordsPrivateRemovePasswordExceptionFunction :
 class PasswordsPrivateGetPlaintextPasswordFunction :
     public UIThreadExtensionFunction {
  public:
-  PasswordsPrivateGetPlaintextPasswordFunction() {}
-  DECLARE_EXTENSION_FUNCTION("passwordsPrivate.GetPlaintextPassword",
+  PasswordsPrivateGetPlaintextPasswordFunction();
+  DECLARE_EXTENSION_FUNCTION("passwordsPrivate.getPlaintextPassword",
                              PASSWORDSPRIVATE_GETPLAINTEXTPASSWORD);
 
  protected:
@@ -77,6 +79,17 @@ class PasswordsPrivateGetPlaintextPasswordFunction :
   ResponseAction Run() override;
 
  private:
+  // Called by the observer when the password has been retrieved so that this
+  // function can return the password value.
+  void ReplyWithPlaintextPassword(const std::string& plaintext_password);
+
+  // Observer used by PasswordsPrivateGetPlaintextPasswordFunction to listen
+  // for when PasswordsPrivateDelegate fetches the requested plaintext
+  // password.
+  class PlaintextPasswordObserver;
+
+  PlaintextPasswordObserver* observer_;
+
   DISALLOW_COPY_AND_ASSIGN(PasswordsPrivateGetPlaintextPasswordFunction);
 };