libservo: Move animation tracking from WindowMethods to delegates (#36400)

This changes removes animation tracking from the `WindowMethods` trait
and moves it to `ServoDelegate` and `WebViewDelegate`.

- Animation changes per-`WebView` are now triggered in the compositor
  only when the value is updated there, rather than right after ticking
  animations.
- Both `WebView` and `Servo` now expose an `animation()` method, so
  tracking animation state actually becomes unecessary in many cases,
  such as that of desktop servoshell, which can just read the value
  when the event loop spins.

Testing: No tests necessary as the API layer is still untested. Later,
tests will be added for the `WebView` API and this can be tested then.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

ports/servoshell/desktop/headless_window.rs

@@ -9,7 +9,7 @@ use std::rc::Rc;
 
 use euclid::num::Zero;
 use euclid::{Length, Scale, Size2D};
-use servo::compositing::windowing::{AnimationState, WindowMethods};
+use servo::compositing::windowing::WindowMethods;
 use servo::servo_geometry::DeviceIndependentPixel;
 use servo::webrender_api::units::{DeviceIntSize, DevicePixel};
 use servo::{RenderingContext, ScreenGeometry, SoftwareRenderingContext};
@@ -20,7 +20,6 @@ use crate::desktop::window_trait::WindowPortsMethods;
 use crate::prefs::ServoShellPreferences;
 
 pub struct Window {
-    animation_state: Cell<AnimationState>,
     fullscreen: Cell<bool>,
     device_pixel_ratio_override: Option<Scale<f32, DeviceIndependentPixel, DevicePixel>>,
     inner_size: Cell<DeviceIntSize>,
@@ -50,7 +49,6 @@ impl Window {
             });
 
         let window = Window {
-            animation_state: Cell::new(AnimationState::Idle),
             fullscreen: Cell::new(false),
             device_pixel_ratio_override,
             inner_size: Cell::new(inner_size),
@@ -120,10 +118,6 @@ impl WindowPortsMethods for Window {
         self.fullscreen.get()
     }
 
-    fn is_animating(&self) -> bool {
-        self.animation_state.get() == AnimationState::Animating
-    }
-
     fn handle_winit_event(&self, _: Rc<RunningAppState>, _: winit::event::WindowEvent) {
         // Not expecting any winit events.
     }
@@ -157,8 +151,4 @@ impl WindowMethods for Window {
         self.device_pixel_ratio_override()
             .unwrap_or_else(|| self.device_hidpi_factor())
     }
-
-    fn set_animation_state(&self, state: AnimationState) {
-        self.animation_state.set(state);
-    }
 }