Update code so 1:1 relation between delegate and router is more clear.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_PASSWORDS_PRIVATE_PASSWORDS_PRIVATE_DELEGATE_H_
 #define CHROME_BROWSER_EXTENSIONS_API_PASSWORDS_PRIVATE_PASSWORDS_PRIVATE_DELEGATE_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 20 matching lines @@
 
 namespace extensions {
 
 // Delegate used by the chrome.passwordsPrivate API to facilitate removing saved
 // passwords and password exceptions and to notify listeners when these values
 // have changed.
 class PasswordsPrivateDelegate : public KeyedService {
  public:
   ~PasswordsPrivateDelegate() override {}
 
-  // An interface used to notify clients (observers) of this object that
-  // saved passwords, password exceptions, and plaintext passwords are ready to
-  // be consumed by the UI. Register an observer via
-  // PasswordsPrivateDelegate::AddObserver().
-  class Observer {
-   public:
-    virtual void OnSavedPasswordsListChanged(
-        const std::vector<api::passwords_private::PasswordUiEntry>& entries) {}
-    virtual void OnPasswordExceptionsListChanged(
-        const std::vector<std::string>& exceptions) {}
-    virtual void OnPlaintextPasswordFetched(
-        const std::string& origin_url,
-        const std::string& username,
-        const std::string& plaintext_password) {}
-
-   protected:
-    virtual ~Observer() {}
-  };
-
-  // Adds |observer| to be notified when password data changes.
-  virtual void AddObserver(Observer* observer) = 0;
-
-  // Removes |observer| from the observer list.
-  virtual void RemoveObserver(Observer* observer) = 0;
+  virtual void SendSavedPasswordsList() = 0;
+  virtual void SendPasswordExceptionsList() = 0;

[stevenjb, 2016/04/06 00:17:08]

These should be commented here.

[hcarmona, 2016/04/06 01:51:23]

Done.

 
   // Removes the saved password entry corresponding to |origin_url| and
   // |username|.
   // |origin_url| The human-readable origin for the URL where the password is
   //     used/ should be obtained using GetHumanReadableOrigin().
   // |username| The username used in conjunction with the saved password.
   virtual void RemoveSavedPassword(
       const std::string& origin_url, const std::string& username) = 0;
 
   // Removes the saved password exception entry corresponding to
@@ skipping 10 matching lines @@
   // |native_window| The Chrome host window; will be used to show an OS-level
   //     authentication dialog if necessary.
   virtual void RequestShowPassword(const std::string& origin_url,
                                    const std::string& username,
                                    content::WebContents* web_contents) = 0;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_PASSWORDS_PRIVATE_PASSWORDS_PRIVATE_DELEGATE_H_