Implement the chrome.passwordsPrivate API.

chrome/common/extensions/api/passwords_private.idl

Index: chrome/common/extensions/api/passwords_private.idl
diff --git a/chrome/common/extensions/api/passwords_private.idl b/chrome/common/extensions/api/passwords_private.idl
index 7dea8b9e6a336bb3f367348ad0a86a6870938490..baeea5c76368f6395e768c1c3499e32b087518a4 100644
--- a/chrome/common/extensions/api/passwords_private.idl
+++ b/chrome/common/extensions/api/passwords_private.idl
@@ -27,8 +27,16 @@ namespace passwordsPrivate {
     DOMString? federationText;
   };
 
+  // Dictionary passed to listeners for the onPlaintextPasswordRetrieved event.
+  dictionary PlaintextPasswordEventParameters {
+    // The LoginPair associated with the retrieved password.
+    LoginPair loginPair;
+
+    // The password in plaintext.
+    DOMString plaintextPassword;
+  };
+
   callback CanAccountBeManagedCallback = void(boolean canAccountBeManaged);
-  callback PlaintextPasswordCallback = void(DOMString plaintextPassword);
 
   interface Functions {
     // Determines whether account's passwords can be managed via
@@ -53,13 +61,12 @@ namespace passwordsPrivate {
 
     // Returns the plaintext password corresponding to |loginPair|. Note that on
     // some operating systems, this call may result in an OS-level
-    // reauthentication.
+    // reauthentication. Once the password has been fetched, it will be returned
+    // via the onPlaintextPasswordRetrieved event.
     //
     // |loginPair|: The LoginPair corresponding to the entry whose password
     //     is to be returned.
-    // |callback|: Callback which will be passed the plaintext password.
-    static void getPlaintextPassword(
-        LoginPair loginPair, PlaintextPasswordCallback callback);
+    static void getPlaintextPassword(LoginPair loginPair);

[stevenjb, 2015/05/29 23:17:02]

nit: We should probably rename this 'requestPlaintextPassword'

[Kyle Horimoto, 2015/06/01 19:14:45]

Done.

   };
 
   interface Events {
@@ -72,9 +79,17 @@ namespace passwordsPrivate {
 
     // Fired when the password exceptions list has changed, meaning that an
     // entry has been added or removed. Note that this event fires as soon as a
-    //  listener is added.
+    // listener is added.
     //
     // |exceptions|: The updated list of password exceptions.
     static void onPasswordExceptionsListChanged(DOMString[] exceptions);
+
+    // Fired when a plaintext password has been fetched in response to a call to
+    // chrome.passwordsPrivate.getPlaintextPassword().
+    //
+    // |loginPair|: The LoginPair whose password was found.
+    // |plaintextPassword|: The plaintext password which was retrieved.
+    static void onPlaintextPasswordRetrieved(
+        PlaintextPasswordEventParameters dict);
   };
 };