Use theme preference from IDE when embedded instead of preference (#6581)

* Use theme preference from IDE when embedded instead of preference

Currently the theme always comes from the preference and ignores what the IDE passes. Since there's no way to un-set the preference (or change it in the UI when embedded) this may prevent it matching the IDE.

This change always uses the IDE preference when embedded. It requires a change in VS Code to pass embed=true when embedding the sidebar since this was missing originally.

packages/devtools_app/lib/src/app.dart

diff --git a/packages/devtools_app/lib/src/app.dart b/packages/devtools_app/lib/src/app.dart
index 2905854..e52b52e 100644
--- a/packages/devtools_app/lib/src/app.dart
+++ b/packages/devtools_app/lib/src/app.dart
@@ -111,10 +111,15 @@
         (e) => DevToolsScreen<void>(ExtensionScreen(e)).screen,
       );
 
-  // TODO(dantup): This does not take IDE preference into account, so results
-  //  in Dark mode embedded sidebar in VS Code.
-  bool get isDarkThemeEnabled => _isDarkThemeEnabled;
-  bool _isDarkThemeEnabled = true;
+  bool get isDarkThemeEnabled {
+    // We use user preference when not embedded. When embedded, we always use
+    // the IDE one (since the user can't access the preference, and the
+    // preference may have been set in an external window and differ from the
+    // IDE theme).
+    return ideTheme.embed ? ideTheme.isDarkMode : _isDarkThemeEnabledPreference;
+  }
+
+  bool _isDarkThemeEnabledPreference = true;
 
   bool get denseModeEnabled => _denseModeEnabled;
   bool _denseModeEnabled = false;
@@ -161,10 +166,10 @@
       },
     );
 
-    _isDarkThemeEnabled = preferences.darkModeTheme.value;
+    _isDarkThemeEnabledPreference = preferences.darkModeTheme.value;
     addAutoDisposeListener(preferences.darkModeTheme, () {
       setState(() {
-        _isDarkThemeEnabled = preferences.darkModeTheme.value;
+        _isDarkThemeEnabledPreference = preferences.darkModeTheme.value;
       });
     });
 

packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md

diff --git a/packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md b/packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md
index 035821c..354a626 100644
--- a/packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md
+++ b/packages/devtools_app/release_notes/NEXT_RELEASE_NOTES.md
@@ -59,6 +59,11 @@
 
 TODO: Remove this section if there are not any general updates.
 
+## VS Code Sidebar updates
+
+* When using VS Code with a light theme, the embedded sidebar provided by DevTools will now also show in the light
+theme [#6581](https://github.com/flutter/devtools/pull/6581)
+
 ## Full commit history
 
 To find a complete list of changes in this release, check out the

packages/devtools_app_shared/lib/src/ui/theme/_ide_theme_web.dart

diff --git a/packages/devtools_app_shared/lib/src/ui/theme/_ide_theme_web.dart b/packages/devtools_app_shared/lib/src/ui/theme/_ide_theme_web.dart
index b2362c4..3e143d6 100644
--- a/packages/devtools_app_shared/lib/src/ui/theme/_ide_theme_web.dart
+++ b/packages/devtools_app_shared/lib/src/ui/theme/_ide_theme_web.dart
@@ -25,6 +25,7 @@
     fontSize:
         _tryParseDouble(queryParams['fontSize']) ?? unscaledDefaultFontSize,
     embed: queryParams['embed'] == 'true',
+    isDarkMode: queryParams['theme'] != 'light',
   );
 
   // If the environment has provided a background color, set it immediately

packages/devtools_app_shared/lib/src/ui/theme/ide_theme.dart

diff --git a/packages/devtools_app_shared/lib/src/ui/theme/ide_theme.dart b/packages/devtools_app_shared/lib/src/ui/theme/ide_theme.dart
index 04e9b37..6f4189e 100644
--- a/packages/devtools_app_shared/lib/src/ui/theme/ide_theme.dart
+++ b/packages/devtools_app_shared/lib/src/ui/theme/ide_theme.dart
@@ -15,12 +15,14 @@
     this.foregroundColor,
     this.fontSize = unscaledDefaultFontSize,
     this.embed = false,
+    this.isDarkMode = true,
   });
 
   final Color? backgroundColor;
   final Color? foregroundColor;
   final double fontSize;
   final bool embed;
+  final bool isDarkMode;
 
   double get fontSizeFactor => fontSize / unscaledDefaultFontSize;
 }

packages/devtools_app_shared/lib/src/ui/theme/theme.dart

diff --git a/packages/devtools_app_shared/lib/src/ui/theme/theme.dart b/packages/devtools_app_shared/lib/src/ui/theme/theme.dart
index 8c9caf4..62fe725 100644
--- a/packages/devtools_app_shared/lib/src/ui/theme/theme.dart
+++ b/packages/devtools_app_shared/lib/src/ui/theme/theme.dart
@@ -203,9 +203,11 @@
 /// override the default DevTools themes with.
 ///
 /// A value of 0.5 would result in all colours being considered light/dark, and
-/// a value of 0.1 allowing around only the 10% darkest/lightest colours by
+/// a value of 0.12 allowing around only the 12% darkest/lightest colours by
 /// Flutter's luminance calculation.
-const _lightDarkLuminanceThreshold = 0.1;
+/// 12% was chosen becaues VS Code's default light background color is #f3f3f3
+/// which is a little under 11%.
+const _lightDarkLuminanceThreshold = 0.12;
 
 bool isValidDarkColor(Color? color) {
   if (color == null) {