Some minor doc typo and diagnostic fixes.

lib/ui/channel_buffers.dart

@@ -330,7 +330,8 @@ class ChannelBuffers {
         'framework has had an opportunity to register a listener. See the ChannelBuffers '
         'API documentation for details on how to configure the channel to expect more '
         'messages, or to expect messages to get discarded:\n'
-        '  https://api.flutter.dev/flutter/dart-ui/ChannelBuffers-class.html'
+        '  https://api.flutter.dev/flutter/dart-ui/ChannelBuffers-class.html\n'
+        'The capacity of the $name channel is ${channel._capacity} message${channel._capacity != 1 ? 's' : ''}.',
       );
     }
   }

lib/ui/window/platform_configuration.cc

@@ -379,17 +379,17 @@ void PlatformConfigurationNativeApi::SetIsolateDebugName(
   UIDartState::Current()->SetDebugName(name);
 }
 
-Dart_PerformanceMode PlatformConfigurationNativeApi::current_performace_mode_ =
+Dart_PerformanceMode PlatformConfigurationNativeApi::current_performance_mode_ =
     Dart_PerformanceMode_Default;
 
 Dart_PerformanceMode PlatformConfigurationNativeApi::GetDartPerformanceMode() {
-  return current_performace_mode_;
+  return current_performance_mode_;
 }
 
 int PlatformConfigurationNativeApi::RequestDartPerformanceMode(int mode) {
   UIDartState::ThrowIfUIOperationsProhibited();
-  current_performace_mode_ = static_cast<Dart_PerformanceMode>(mode);
-  return Dart_SetPerformanceMode(current_performace_mode_);
+  current_performance_mode_ = static_cast<Dart_PerformanceMode>(mode);
+  return Dart_SetPerformanceMode(current_performance_mode_);
 }
 
 Dart_Handle PlatformConfigurationNativeApi::GetPersistentIsolateData() {

lib/ui/window/platform_configuration.h

@@ -30,7 +30,7 @@ class Scene;
 /// @brief An enum for defining the different kinds of accessibility features
 ///        that can be enabled by the platform.
 ///
-///         Must match the `AccessibilityFeatureFlag` enum in framework.
+///         Must match the `AccessibilityFeatures` class in framework.
 enum class AccessibilityFeatureFlag : int32_t {
   kAccessibleNavigation = 1 << 0,
   kInvertColors = 1 << 1,
@@ -538,7 +538,7 @@ class PlatformConfigurationNativeApi {
   static void RegisterBackgroundIsolate(int64_t root_isolate_token);
 
  private:
-  static Dart_PerformanceMode current_performace_mode_;
+  static Dart_PerformanceMode current_performance_mode_;
 };
 
 }  // namespace flutter

shell/platform/common/client_wrapper/include/flutter/plugin_registrar.h

@@ -49,8 +49,8 @@ class PluginRegistrar {
   // Takes ownership of |plugin|.
   //
   // Plugins are not required to call this method if they have other lifetime
-  // management, but this is a convient place for plugins to be owned to ensure
-  // that they stay valid for any registered callbacks.
+  // management, but this is a convenient place for plugins to be owned to
+  // ensure that they stay valid for any registered callbacks.
   void AddPlugin(std::unique_ptr<Plugin> plugin);
 
  protected:

shell/platform/darwin/ios/framework/Headers/FlutterPlugin.h

@@ -28,15 +28,15 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  * Called if this has been registered for `UIApplicationDelegate` callbacks.
  *
- * @return `NO` if this vetoes application launch.
+ * @return `NO` if this vetos application launch.
  */
 - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions;
 
 /**
  * Called if this has been registered for `UIApplicationDelegate` callbacks.
  *
- * @return `NO` if this vetoes application launch.
+ * @return `NO` if this vetos application launch.
  */
 - (BOOL)application:(UIApplication*)application
     willFinishLaunchingWithOptions:(NSDictionary*)launchOptions;

shell/platform/darwin/ios/framework/Headers/FlutterPluginAppLifeCycleDelegate.h

@@ -16,25 +16,25 @@ FLUTTER_DARWIN_EXPORT
 @interface FlutterPluginAppLifeCycleDelegate : NSObject <UNUserNotificationCenterDelegate>
 
 /**
- * Registers `delegate` to receive life cycle callbacks via this FlutterPluginAppLifecycleDelegate
+ * Registers `delegate` to receive life cycle callbacks via this FlutterPluginAppLifeCycleDelegate
  * as long as it is alive.
  *
- * `delegate` will only referenced weakly.
+ * `delegate` will only be referenced weakly.
  */
 - (void)addDelegate:(NSObject<FlutterApplicationLifeCycleDelegate>*)delegate;
 
 /**
  * Calls all plugins registered for `UIApplicationDelegate` callbacks.
  *
- * @return `NO` if any plugin vetoes application launch.
+ * @return `NO` if any plugin vetos application launch.
  */
 - (BOOL)application:(UIApplication*)application
     didFinishLaunchingWithOptions:(NSDictionary*)launchOptions;
 
 /**
  * Calls all plugins registered for `UIApplicationDelegate` callbacks.
  *
- * @return `NO` if any plugin vetoes application launch.
+ * @return `NO` if any plugin vetos application launch.
  */
 - (BOOL)application:(UIApplication*)application
     willFinishLaunchingWithOptions:(NSDictionary*)launchOptions;