Correct capitalisation of Xcode (#7796)

Ref: https://developer.apple.com/xcode/
diff --git a/packages/flutter_tools/lib/executable.dart b/packages/flutter_tools/lib/executable.dart
index d23b6d5..f0f4142 100644
--- a/packages/flutter_tools/lib/executable.dart
+++ b/packages/flutter_tools/lib/executable.dart
@@ -115,7 +115,7 @@
     context.putIfAbsent(ToolConfiguration, () => new ToolConfiguration());
     context.putIfAbsent(Config, () => new Config());
     context.putIfAbsent(OperatingSystemUtils, () => new OperatingSystemUtils());
-    context.putIfAbsent(XCode, () => new XCode());
+    context.putIfAbsent(Xcode, () => new Xcode());
     context.putIfAbsent(IOSSimulatorUtils, () => new IOSSimulatorUtils());
     context.putIfAbsent(SimControl, () => new SimControl());
     context.putIfAbsent(Usage, () => new Usage());
diff --git a/packages/flutter_tools/lib/src/commands/run.dart b/packages/flutter_tools/lib/src/commands/run.dart
index f0ce0c9..38385b3 100644
--- a/packages/flutter_tools/lib/src/commands/run.dart
+++ b/packages/flutter_tools/lib/src/commands/run.dart
@@ -156,7 +156,7 @@
   void printNoConnectedDevices() {
     super.printNoConnectedDevices();
     if (getCurrentHostPlatform() == HostPlatform.darwin_x64 &&
-        XCode.instance.isInstalledAndMeetsVersionCheck) {
+        Xcode.instance.isInstalledAndMeetsVersionCheck) {
       printStatus('');
       printStatus('To run on a simulator, launch it first: open -a Simulator.app');
       printStatus('');
diff --git a/packages/flutter_tools/lib/src/ios/devices.dart b/packages/flutter_tools/lib/src/ios/devices.dart
index fd7e705..f145a5a 100644
--- a/packages/flutter_tools/lib/src/ios/devices.dart
+++ b/packages/flutter_tools/lib/src/ios/devices.dart
@@ -299,7 +299,7 @@
 
     if (installationResult != 0) {
       printError('Could not install ${bundle.path} on $id.');
-      printError('Try launching XCode and selecting "Product > Run" to fix the problem:');
+      printError('Try launching Xcode and selecting "Product > Run" to fix the problem:');
       printError('  open ios/Runner.xcodeproj');
       printError('');
       return new LaunchResult.failed();
diff --git a/packages/flutter_tools/lib/src/ios/ios_workflow.dart b/packages/flutter_tools/lib/src/ios/ios_workflow.dart
index 213f505..bd55ead 100644
--- a/packages/flutter_tools/lib/src/ios/ios_workflow.dart
+++ b/packages/flutter_tools/lib/src/ios/ios_workflow.dart
@@ -13,7 +13,7 @@
 import '../doctor.dart';
 import 'mac.dart';
 
-XCode get xcode => XCode.instance;
+Xcode get xcode => Xcode.instance;
 
 class IOSWorkflow extends DoctorValidator implements Workflow {
   IOSWorkflow() : super('iOS toolchain - develop for iOS devices');
@@ -61,7 +61,7 @@
     if (xcode.isInstalled) {
       xcodeStatus = ValidationType.installed;
 
-      messages.add(new ValidationMessage('XCode at ${xcode.xcodeSelectPath}'));
+      messages.add(new ValidationMessage('Xcode at ${xcode.xcodeSelectPath}'));
 
       xcodeVersionInfo = xcode.xcodeVersionText;
       if (xcodeVersionInfo.contains(','))
@@ -71,7 +71,7 @@
       if (!xcode.isInstalledAndMeetsVersionCheck) {
         xcodeStatus = ValidationType.partial;
         messages.add(new ValidationMessage.error(
-          'Flutter requires a minimum XCode version of $kXcodeRequiredVersionMajor.$kXcodeRequiredVersionMinor.0.\n'
+          'Flutter requires a minimum Xcode version of $kXcodeRequiredVersionMajor.$kXcodeRequiredVersionMinor.0.\n'
           'Download the latest version or update via the Mac App Store.'
         ));
       }
@@ -79,13 +79,13 @@
       if (!xcode.eulaSigned) {
         xcodeStatus = ValidationType.partial;
         messages.add(new ValidationMessage.error(
-          'XCode end user license agreement not signed; open XCode or run the command \'sudo xcodebuild -license\'.'
+          'Xcode end user license agreement not signed; open Xcode or run the command \'sudo xcodebuild -license\'.'
         ));
       }
     } else {
       xcodeStatus = ValidationType.missing;
       messages.add(new ValidationMessage.error(
-        'XCode not installed; this is necessary for iOS development.\n'
+        'Xcode not installed; this is necessary for iOS development.\n'
         'Download at https://developer.apple.com/xcode/download/.'
       ));
     }
@@ -119,7 +119,7 @@
         if (result.exitCode == 0 && result.stdout.isNotEmpty && !exitsHappy(<String>['ideviceName'])) {
           brewStatus = ValidationType.partial;
           messages.add(new ValidationMessage.error(
-            'libimobiledevice is incompatible with the installed XCode version. To update, run:\n'
+            'libimobiledevice is incompatible with the installed Xcode version. To update, run:\n'
             'brew uninstall libimobiledevice\n'
             'brew install --HEAD libimobiledevice'
           ));
diff --git a/packages/flutter_tools/lib/src/ios/mac.dart b/packages/flutter_tools/lib/src/ios/mac.dart
index 13114c0..95231da 100644
--- a/packages/flutter_tools/lib/src/ios/mac.dart
+++ b/packages/flutter_tools/lib/src/ios/mac.dart
@@ -23,8 +23,8 @@
 const int kXcodeRequiredVersionMajor = 7;
 const int kXcodeRequiredVersionMinor = 0;
 
-class XCode {
-  XCode() {
+class Xcode {
+  Xcode() {
     _eulaSigned = false;
 
     try {
@@ -58,8 +58,8 @@
     }
   }
 
-  /// Returns [XCode] active in the current app context.
-  static XCode get instance => context[XCode];
+  /// Returns [Xcode] active in the current app context.
+  static Xcode get instance => context[Xcode];
 
   bool get isInstalledAndMeetsVersionCheck => isInstalled && xcodeVersionSatisfactory;
 
@@ -202,7 +202,7 @@
       printError('  ${plistFile.absolute.path}');
       printError('');
     }
-    printError("Try launching XCode and selecting 'Product > Build' to fix the problem:");
+    printError("Try launching Xcode and selecting 'Product > Build' to fix the problem:");
     printError("  open ios/Runner.xcodeproj");
     return;
   }
diff --git a/packages/flutter_tools/lib/src/ios/simulators.dart b/packages/flutter_tools/lib/src/ios/simulators.dart
index 5dffffa..4b0ec37 100644
--- a/packages/flutter_tools/lib/src/ios/simulators.dart
+++ b/packages/flutter_tools/lib/src/ios/simulators.dart
@@ -43,7 +43,7 @@
   static IOSSimulatorUtils get instance => context[IOSSimulatorUtils];
 
   List<IOSSimulator> getAttachedDevices() {
-    if (!XCode.instance.isInstalledAndMeetsVersionCheck)
+    if (!Xcode.instance.isInstalledAndMeetsVersionCheck)
       return <IOSSimulator>[];
 
     return SimControl.instance.getConnectedDevices().map((SimDevice device) {
diff --git a/packages/flutter_tools/test/daemon_test.dart b/packages/flutter_tools/test/daemon_test.dart
index 28a7ff8..4e0a4ef 100644
--- a/packages/flutter_tools/test/daemon_test.dart
+++ b/packages/flutter_tools/test/daemon_test.dart
@@ -36,7 +36,7 @@
       appContext.setVariable(Logger, notifyingLogger);
       appContext.setVariable(Doctor, new Doctor());
       if (platform.isMacOS)
-        appContext.setVariable(XCode, new XCode());
+        appContext.setVariable(Xcode, new Xcode());
       appContext.setVariable(DeviceManager, new MockDeviceManager());
     });
 
diff --git a/packages/flutter_tools/test/src/context.dart b/packages/flutter_tools/test/src/context.dart
index 02f1d99..e694029 100644
--- a/packages/flutter_tools/test/src/context.dart
+++ b/packages/flutter_tools/test/src/context.dart
@@ -60,7 +60,7 @@
       when(os.isWindows).thenReturn(false);
       return os;
     });
-    testContext.putIfAbsent(XCode, () => new XCode());
+    testContext.putIfAbsent(Xcode, () => new Xcode());
     testContext.putIfAbsent(IOSSimulatorUtils, () {
       MockIOSSimulatorUtils mock = new MockIOSSimulatorUtils();
       when(mock.getAttachedDevices()).thenReturn(<IOSSimulator>[]);
diff --git a/packages/flutter_tools/test/src/ios/ios_workflow_test.dart b/packages/flutter_tools/test/src/ios/ios_workflow_test.dart
index 1c077a6..0a6921f 100644
--- a/packages/flutter_tools/test/src/ios/ios_workflow_test.dart
+++ b/packages/flutter_tools/test/src/ios/ios_workflow_test.dart
@@ -13,9 +13,9 @@
 
 void main() {
   group('iOS Workflow validation', () {
-    MockXCode xcode;
+    MockXcode xcode;
     setUp(() {
-      xcode = new MockXCode();
+      xcode = new MockXcode();
     });
 
     testUsingContext('Emit missing status when nothing is installed', () async {
@@ -25,14 +25,14 @@
         ..hasIosDeploy = false;
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.missing);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when Xcode is not installed', () async {
       when(xcode.isInstalled).thenReturn(false);
       IOSWorkflowTestTarget workflow = new IOSWorkflowTestTarget();
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when Xcode version too low', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -43,7 +43,7 @@
       IOSWorkflowTestTarget workflow = new IOSWorkflowTestTarget();
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when Xcode EULA not signed', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -54,7 +54,7 @@
       IOSWorkflowTestTarget workflow = new IOSWorkflowTestTarget();
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when homebrew not installed', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -66,7 +66,7 @@
         ..hasHomebrew = false;
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when ios-deploy is not installed', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -78,7 +78,7 @@
         ..hasIosDeploy = false;
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Emits partial status when ios-deploy version is too low', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -90,7 +90,7 @@
         ..iosDeployVersionText = '1.8.0';
       ValidationResult result = await workflow.validate();
       expect(result.type, ValidationType.partial);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
 
     testUsingContext('Succeeds when all checks pass', () async {
       when(xcode.isInstalled).thenReturn(true);
@@ -100,11 +100,11 @@
       when(xcode.eulaSigned).thenReturn(true);
       ValidationResult result = await new IOSWorkflowTestTarget().validate();
       expect(result.type, ValidationType.installed);
-    }, overrides: <Type, Generator>{ XCode: () => xcode });
+    }, overrides: <Type, Generator>{ Xcode: () => xcode });
   });
 }
 
-class MockXCode extends Mock implements XCode {}
+class MockXcode extends Mock implements Xcode {}
 
 class IOSWorkflowTestTarget extends IOSWorkflow {
   @override