[flutter_tool] Use curly braces around single statment control structures (#40446)

diff --git a/packages/flutter_tools/lib/src/vmservice.dart b/packages/flutter_tools/lib/src/vmservice.dart
index d095b3e..a5af8de 100644
--- a/packages/flutter_tools/lib/src/vmservice.dart
+++ b/packages/flutter_tools/lib/src/vmservice.dart
@@ -72,15 +72,17 @@
     printTrace('Exception attempting to connect to Observatory: $e');
     printTrace('This was attempt #$attempts. Will retry in $delay.');
 
-    if (attempts == 10)
+    if (attempts == 10) {
       printStatus('This is taking longer than expected...');
+    }
 
     // Delay next attempt.
     await Future<void>.delayed(delay);
 
     // Back off exponentially, up to 1600ms per attempt.
-    if (delay < const Duration(seconds: 1))
+    if (delay < const Duration(seconds: 1)) {
       delay *= 2;
+    }
   }
 
   final WebSocketConnector constructor = context.get<WebSocketConnector>() ?? io.WebSocket.connect;
@@ -121,12 +123,15 @@
         final bool force = params.asMap['force'] ?? false;
         final bool pause = params.asMap['pause'] ?? false;
 
-        if (isolateId is! String || isolateId.isEmpty)
+        if (isolateId is! String || isolateId.isEmpty) {
           throw rpc.RpcException.invalidParams('Invalid \'isolateId\': $isolateId');
-        if (force is! bool)
+        }
+        if (force is! bool) {
           throw rpc.RpcException.invalidParams('Invalid \'force\': $force');
-        if (pause is! bool)
+        }
+        if (pause is! bool) {
           throw rpc.RpcException.invalidParams('Invalid \'pause\': $pause');
+        }
 
         try {
           await reloadSources(isolateId, force: force, pause: pause);
@@ -149,8 +154,9 @@
       _peer.registerMethod('hotRestart', (rpc.Parameters params) async {
         final bool pause = params.asMap['pause'] ?? false;
 
-        if (pause is! bool)
+        if (pause is! bool) {
           throw rpc.RpcException.invalidParams('Invalid \'pause\': $pause');
+        }
 
         try {
           await restart(pause: pause);
@@ -185,13 +191,15 @@
     if (compileExpression != null) {
       _peer.registerMethod('compileExpression', (rpc.Parameters params) async {
         final String isolateId = params['isolateId'].asString;
-        if (isolateId is! String || isolateId.isEmpty)
+        if (isolateId is! String || isolateId.isEmpty) {
           throw rpc.RpcException.invalidParams(
               'Invalid \'isolateId\': $isolateId');
+        }
         final String expression = params['expression'].asString;
-        if (expression is! String || expression.isEmpty)
+        if (expression is! String || expression.isEmpty) {
           throw rpc.RpcException.invalidParams(
               'Invalid \'expression\': $expression');
+        }
         final List<String> definitions =
             List<String>.from(params['definitions'].asList);
         final List<String> typeDefinitions =
@@ -399,8 +407,9 @@
   dynamic collection,
   ServiceObjectOwner owner,
 ) {
-  if (collection is ServiceMap)
+  if (collection is ServiceMap) {
     return;
+  }
   if (collection is Map<String, dynamic>) {
     _upgradeMap(collection, owner);
   } else if (collection is List) {
@@ -444,11 +453,13 @@
     ServiceObjectOwner owner,
     Map<String, dynamic> map,
   ) {
-    if (map == null)
+    if (map == null) {
       return null;
+    }
 
-    if (!_isServiceMap(map))
+    if (!_isServiceMap(map)) {
       throw VMServiceObjectLoadError('Expected a service map', map);
+    }
 
     final String type = _stripRef(map['type']);
 
@@ -506,8 +517,9 @@
 
   /// If this is not already loaded, load it. Otherwise reload.
   Future<ServiceObject> load() async {
-    if (loaded)
+    if (loaded) {
       return this;
+    }
     return reload();
   }
 
@@ -527,8 +539,9 @@
     // We should always reload the VM.
     // We can't reload objects without an id.
     // We shouldn't reload an immutable and already loaded object.
-    if (!isVM && (!hasId || (immutable && loaded)))
+    if (!isVM && (!hasId || (immutable && loaded))) {
       return this;
+    }
 
     if (_inProgressReload == null) {
       final Completer<ServiceObject> completer = Completer<ServiceObject>();
@@ -695,8 +708,9 @@
 
   @override
   void _update(Map<String, dynamic> map, bool mapIsRef) {
-    if (mapIsRef)
+    if (mapIsRef) {
       return;
+    }
 
     // Upgrade the collection. A side effect of this call is that any new
     // isolates in the map are created and added to the isolate cache.
@@ -704,8 +718,9 @@
     _loaded = true;
 
     _pid = map['pid'];
-    if (map['_heapAllocatedMemoryUsage'] != null)
+    if (map['_heapAllocatedMemoryUsage'] != null) {
       _heapAllocatedMemoryUsage = map['_heapAllocatedMemoryUsage'];
+    }
     _maxRSS = map['_maxRSS'];
     _embedder = map['_embedder'];
 
@@ -766,8 +781,9 @@
   void _removeDeadIsolates(List<Isolate> newIsolates) {
     // Build a set of new isolates.
     final Set<String> newIsolateSet = <String>{};
-    for (Isolate iso in newIsolates)
+    for (Isolate iso in newIsolates) {
       newIsolateSet.add(iso.id);
+    }
 
     // Remove any old isolates which no longer exist.
     final List<String> toRemove = <String>[];
@@ -844,8 +860,9 @@
 
   static String _truncate(String message, int width, String ellipsis) {
     assert(ellipsis.length < width);
-    if (message.length <= width)
+    if (message.length <= width) {
       return message;
+    }
     return message.substring(0, width - ellipsis.length) + ellipsis;
   }
 
@@ -978,8 +995,9 @@
   Future<void> refreshViews({ bool waitForViews = false }) async {
     assert(waitForViews != null);
     assert(loaded);
-    if (!isFlutterEngine)
+    if (!isFlutterEngine) {
       return;
+    }
     int failCount = 0;
     while (true) {
       _viewCache.clear();
@@ -988,11 +1006,13 @@
       // This message updates all the views of every isolate.
       await vmService.vm.invokeRpc<ServiceObject>(
           '_flutter.listViews', truncateLogs: false);
-      if (_viewCache.values.isNotEmpty || !waitForViews)
+      if (_viewCache.values.isNotEmpty || !waitForViews) {
         return;
+      }
       failCount += 1;
-      if (failCount == 5) // waited 200ms
+      if (failCount == 5) { // waited 200ms
         printStatus('Flutter is taking longer than expected to report its views. Still trying...');
+      }
       await Future<void>.delayed(const Duration(milliseconds: 50));
       await reload();
     }
@@ -1005,8 +1025,9 @@
   }
 
   List<FlutterView> allViewsWithName(String isolateFilter) {
-    if (_viewCache.values.isEmpty)
+    if (_viewCache.values.isEmpty) {
       return null;
+    }
     return _viewCache.values.where(
       (FlutterView v) => v.uiIsolate.name.contains(isolateFilter)
     ).toList();
@@ -1081,8 +1102,9 @@
 
   @override
   ServiceObject getFromMap(Map<String, dynamic> map) {
-    if (map == null)
+    if (map == null) {
       return null;
+    }
     final String mapType = _stripRef(map['type']);
     if (mapType == 'Isolate') {
       // There are sometimes isolate refs in ServiceEvents.
@@ -1097,8 +1119,9 @@
     }
     // Build the object from the map directly.
     serviceObject = ServiceObject._fromMap(this, map);
-    if ((serviceObject != null) && serviceObject.canCache)
+    if ((serviceObject != null) && serviceObject.canCache) {
       _cache[mapId] = serviceObject;
+    }
     return serviceObject;
   }
 
@@ -1135,8 +1158,9 @@
 
   @override
   void _update(Map<String, dynamic> map, bool mapIsRef) {
-    if (mapIsRef)
+    if (mapIsRef) {
       return;
+    }
     _loaded = true;
 
     final int startTimeMillis = map['startTime'];
@@ -1199,8 +1223,9 @@
       return await invokeRpcRaw(method, params: params);
     } on rpc.RpcException catch (e) {
       // If an application is not using the framework
-      if (e.code == rpc_error_code.METHOD_NOT_FOUND)
+      if (e.code == rpc_error_code.METHOD_NOT_FOUND) {
         return null;
+      }
       rethrow;
     }
   }
@@ -1279,8 +1304,9 @@
   Future<List<int>> flutterDebugSaveCompilationTrace() async {
     final Map<String, dynamic> result =
       await invokeFlutterExtensionRpcRaw('ext.flutter.saveCompilationTrace');
-    if (result != null && result['value'] is List<dynamic>)
+    if (result != null && result['value'] is List<dynamic>) {
       return result['value'].cast<int>();
+    }
     return null;
   }
 
@@ -1294,8 +1320,9 @@
       'ext.flutter.platformOverride',
       params: platform != null ? <String, dynamic>{'value': platform} : <String, String>{},
     );
-    if (result != null && result['value'] is String)
+    if (result != null && result['value'] is String) {
       return result['value'];
+    }
     return 'unknown';
   }
 
@@ -1393,8 +1420,9 @@
         // launch errors.
         if (event.kind == ServiceEvent.kIsolateRunnable) {
           printTrace('Isolate is runnable.');
-          if (!completer.isCompleted)
+          if (!completer.isCompleted) {
             completer.complete();
+          }
         }
       });
     await owner.vm.runInView(viewId,