Fix wide gamut macos integration test (#184427)

Fixes https://github.com/flutter/flutter/issues/182589.

CI machines don't have physical monitors, and the default virtual screen
given by MacOS doesn't report wide gamut support. This caused the check
in
https://github.com/flutter/flutter/blob/413244e157d7713a37ebcd892630c5bd5f6d4d30/engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm#L808
to downgrade the color mode for the tests to sRGB, even though the
hardware supports wide-gamut.

This change overrides `updateWideGamutForScreen` to always enable wide
gamut for this test in CI.

This change also updates .ci.yaml to ensure that this test runs on Apple
Silicon hardware

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [AI contribution guidelines] and understand my
responsibilities, or I am not using AI tools.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

.ci.yaml

diff --git a/.ci.yaml b/.ci.yaml
index cb3dd3a..51e49f1 100644
--- a/.ci.yaml
+++ b/.ci.yaml
@@ -5398,6 +5398,8 @@
       tags: >
         ["devicelab", "hostonly", "mac"]
       task_name: wide_gamut_macos
+    drone_dimensions:
+      - gpu=apple
 
   - name: Mac_x64_ios hot_mode_dev_cycle_ios__benchmark
     recipe: devicelab/devicelab_drone

dev/integration_tests/wide_gamut_test/macos/Runner/MainFlutterWindow.swift

diff --git a/dev/integration_tests/wide_gamut_test/macos/Runner/MainFlutterWindow.swift b/dev/integration_tests/wide_gamut_test/macos/Runner/MainFlutterWindow.swift
new file mode 100644
index 0000000..c51076d
--- /dev/null
+++ b/dev/integration_tests/wide_gamut_test/macos/Runner/MainFlutterWindow.swift
@@ -0,0 +1,45 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import Cocoa
+import FlutterMacOS
+import Foundation
+
+class WideGamutViewController: FlutterViewController {
+
+  // This intercepts the private engine method called during window moves/resizes.
+  // By overriding it, we stop the engine from checking the screen and disabling wide-gamut.
+  @objc(updateWideGamutForScreen)
+  func updateWideGamutForScreen() {
+    let flutterView = self.view
+    let mySelector = Selector("setEnableWideGamut:")
+
+    // 1. Check if the object actually has this method
+    if flutterView.responds(to: mySelector) {
+      // 2. Call the method using reflection.
+      flutterView.perform(mySelector, with: true)
+    }
+  }
+
+  override func viewWillAppear() {
+    super.viewWillAppear()
+    // Force the surface to 10-bit during the initial view loading sequence.
+    self.updateWideGamutForScreen()
+  }
+}
+
+class MainFlutterWindow: NSWindow {
+  override func awakeFromNib() {
+    // Instantiate our custom subclass instead of the standard FlutterViewController.
+    let flutterViewController = WideGamutViewController()
+
+    let windowFrame = self.frame
+    self.contentViewController = flutterViewController
+    self.setFrame(windowFrame, display: true)
+
+    RegisterGeneratedPlugins(registry: flutterViewController)
+
+    super.awakeFromNib()
+  }
+}