Split FlowDelegate into DeviceFlowDelegate and InstalledFlowDelegate.

Each flow invokes a non-overlapping set of methods. There doesn't appear
to be any benefit in having both flows use a common trait. The benefit
of splitting the traits is that it makes it clear which methods need to
be updated for each flow type where previously comments were required to
communicate that information.

src/authenticator_delegate.rs

@@ -75,9 +75,9 @@ pub trait AuthenticatorDelegate: Send + Sync {
     fn token_refresh_failed(&self, _: &RefreshError) {}
 }
 
-/// FlowDelegate methods are called when an OAuth flow needs to ask the application what to do in
-/// certain cases.
-pub trait FlowDelegate: Send + Sync {
+/// DeviceFlowDelegate methods are called when a device flow needs to ask the
+/// application what to do in certain cases.
+pub trait DeviceFlowDelegate: Send + Sync {
     /// Called if the request code is expired. You will have to start over in this case.
     /// This will be the last call the delegate receives.
     /// Given `DateTime` is the expiration date
@@ -91,22 +91,14 @@ pub trait FlowDelegate: Send + Sync {
     /// Can be used to print progress information, or decide to time-out.
     ///
     /// If the returned `Retry` variant is a duration.
-    /// # Notes
-    /// * Only used in `DeviceFlow`. Return value will only be used if it
-    /// is larger than the interval desired by the server.
     fn pending(&self, _: &PollInformation) -> Retry {
         Retry::After(Duration::from_secs(5))
     }
 
-    /// Configure a custom redirect uri if needed.
-    fn redirect_uri(&self) -> Option<&str> {
-        None
-    }
     /// The server has returned a `user_code` which must be shown to the user,
     /// along with the `verification_url`.
     /// # Notes
     /// * Will be called exactly once, provided we didn't abort during `request_code` phase.
-    /// * Will only be called if the Authenticator's flow_type is `DeviceFlow`.
     fn present_user_code(&self, pi: &PollInformation) {
         println!(
             "Please enter {} at {} and grant access to this application",
@@ -118,8 +110,16 @@ pub trait FlowDelegate: Send + Sync {
             pi.expires_at.with_timezone(&Local)
         );
     }
+}
+
+/// InstalledFlowDelegate methods are called when an installed flow needs to ask
+/// the application what to do in certain cases.
+pub trait InstalledFlowDelegate: Send + Sync {
+    /// Configure a custom redirect uri if needed.
+    fn redirect_uri(&self) -> Option<&str> {
+        None
+    }
 
-    /// This method is used by the InstalledFlow.
     /// We need the user to navigate to a URL using their browser and potentially paste back a code
     /// (or maybe not). Whether they have to enter a code depends on the InstalledFlowReturnMethod
     /// used.
@@ -167,11 +167,16 @@ async fn present_user_url(
 
 /// Uses all default implementations by AuthenticatorDelegate, and makes the trait's
 /// implementation usable in the first place.
-#[derive(Clone)]
+#[derive(Copy, Clone)]
 pub struct DefaultAuthenticatorDelegate;
 impl AuthenticatorDelegate for DefaultAuthenticatorDelegate {}
 
-/// Uses all default implementations in the FlowDelegate trait.
-#[derive(Clone)]
-pub struct DefaultFlowDelegate;
-impl FlowDelegate for DefaultFlowDelegate {}
+/// Uses all default implementations in the DeviceFlowDelegate trait.
+#[derive(Copy, Clone)]
+pub struct DefaultDeviceFlowDelegate;
+impl DeviceFlowDelegate for DefaultDeviceFlowDelegate {}
+
+/// Uses all default implementations in the DeviceFlowDelegate trait.
+#[derive(Copy, Clone)]
+pub struct DefaultInstalledFlowDelegate;
+impl InstalledFlowDelegate for DefaultInstalledFlowDelegate {}