[Color Picker] Handle default display refresh-rate sentinel values (#49973)

## Summary of the Pull Request

Treats `dmDisplayFrequency` values `0` and `1` as the display hardware's
default refresh rate instead of literal frequencies.

Color Picker now retains its existing 60 Hz fallback for these sentinel
values, preventing a timer interval overflow for `0` and one-second
sampling for `1`. Valid refresh rates greater than `1` remain unchanged.

## PR Checklist

- [x] Closes: #49971
- [ ] **Communication:** The issue has been filed for triage; this
change has not yet been discussed with core contributors
- [x] **Tests:** Added/updated and all pass
- [x] **Localization:** No end-user-facing strings were added
- [ ] **Dev docs:** Not applicable for this implementation-only bug fix
- [ ] **New binaries:** No new binaries were added
- [ ] **Documentation updated:** Not applicable; no user-facing
documentation contract changed

## Detailed Description of the Pull Request / Additional comments

`GetMainDisplayRefreshRate` now accepts a reported refresh rate only
when it is greater than `1`. Otherwise, it keeps the existing 60 Hz
fallback.

A small test seam and unit tests cover reported values `0`, `1`, `60`,
and `144`. The correct `InternalsVisibleTo` entry is added for the
existing `ColorPickerUI.UnitTests` assembly.

This issue was discovered while reviewing #49855, but it is an existing
bug and this PR targets current `main` independently. Since #49855 also
changes the refresh-rate code, whichever PR merges second may need a
trivial rebase that preserves the `> 1` sentinel handling.

No settings schema, IPC contract, dependencies, installer content, or
production binaries were changed.

## Validation Steps Performed

- `tools\build\build-essentials.cmd -Platform x64 -Configuration Debug`:
passed with exit code 0, 0 warnings, and 0 errors.
- `tools\build\build.cmd -Platform x64 -Configuration Debug` from
`ColorPickerUI.UnitTests`: passed with exit code 0, 0 warnings, and 0
errors.
- Full `vstest.console.exe` run for `ColorPickerUI.UnitTests.dll`: **382
passed, 0 failed**.
- `git diff --check`: passed.

Co-authored-by: Yu Leng (from Dev Box) <yuleng@microsoft.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 7b3fb20d-6e9d-4fef-a5cd-f8921d28c220

src/modules/colorPicker/ColorPickerUI.UnitTests/Mouse/DisplayRefreshRateTest.cs

@@ -0,0 +1,23 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using ColorPicker.Mouse;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace ColorPicker.UnitTests.Mouse
+{
+    [TestClass]
+    public class DisplayRefreshRateTest
+    {
+        [TestMethod]
+        [DataRow(0, 60.0)]
+        [DataRow(1, 60.0)]
+        [DataRow(60, 60.0)]
+        [DataRow(144, 144.0)]
+        public void GetDisplayRefreshRateOrDefault_HandlesDefaultRefreshRateSentinels(int displayFrequency, double expectedRefreshRate)
+        {
+            Assert.AreEqual(expectedRefreshRate, MouseInfoProvider.GetDisplayRefreshRateOrDefault((uint)displayFrequency));
+        }
+    }
+}

src/modules/colorPicker/ColorPickerUI/Bootstrapper.cs

@@ -7,6 +7,7 @@ using System.ComponentModel.Composition.Hosting;
 using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("UnitTest-ColorPickerUI")]
+[assembly: InternalsVisibleTo("ColorPickerUI.UnitTests")]
 
 namespace ColorPicker
 {

src/modules/colorPicker/ColorPickerUI/Mouse/MouseInfoProvider.cs

@@ -21,6 +21,8 @@ namespace ColorPicker.Mouse
     [PartCreationPolicy(CreationPolicy.Shared)]
     public class MouseInfoProvider : IMouseInfoProvider
     {
+        private const double DefaultDisplayRefreshRate = 60.0;
+
         private readonly double _mousePullInfoIntervalInMs;
         private readonly DispatcherTimer _timer = new DispatcherTimer();
         private readonly MouseHook _mouseHook;
@@ -123,13 +125,13 @@ namespace ColorPicker.Mouse
 
         private static double GetMainDisplayRefreshRate()
         {
-            double refreshRate = 60.0;
+            double refreshRate = DefaultDisplayRefreshRate;
 
             foreach (var monitor in MonitorResolutionHelper.AllMonitors)
             {
                 if (monitor.IsPrimary && EnumDisplaySettingsW(monitor.Name, ENUM_CURRENT_SETTINGS, out DEVMODEW lpDevMode))
                 {
-                    refreshRate = (double)lpDevMode.dmDisplayFrequency;
+                    refreshRate = GetDisplayRefreshRateOrDefault(lpDevMode.dmDisplayFrequency);
                     break;
                 }
             }
@@ -137,6 +139,10 @@ namespace ColorPicker.Mouse
             return refreshRate;
         }
 
+        // EnumDisplaySettings uses 0 and 1 to represent the hardware default refresh rate.
+        internal static double GetDisplayRefreshRateOrDefault(uint displayFrequency)
+            => displayFrequency > 1 ? displayFrequency : DefaultDisplayRefreshRate;
+
         private void AppStateMonitor_AppClosed(object sender, EventArgs e)
         {
             DisposeHook();