delay looking for android devices

packages/flutter_tools/lib/src/install.dart

@@ -14,15 +14,17 @@ import 'device.dart';
 class InstallCommand extends Command {
   final name = 'install';
   final description = 'Install your Flutter app on attached devices.';
+
   AndroidDevice android = null;
-  InstallCommand([this.android]) {
+
+  InstallCommand([this.android]);
+
+  @override
+  Future<int> run() async {
     if (android == null) {
       android = new AndroidDevice();
     }
-  }
 
-  @override
-  Future<int> run() async {
     if (install()) {
       return 0;
     } else {

packages/flutter_tools/lib/src/listen.dart

@@ -34,14 +34,14 @@ class ListenCommand extends Command {
         defaultsTo: '.',
         abbr: 't',
         help: 'Target app path or filename to start.');
+  }
 
+  @override
+  Future<int> run() async {
     if (android == null) {
       android = new AndroidDevice();
     }
-  }
 
-  @override
-  Future<int> run() async {
     if (argResults.rest.length > 0) {
       watchCommand = _initWatchCommand(argResults.rest);
     } else {

packages/flutter_tools/lib/src/logs.dart

@@ -21,13 +21,14 @@ class LogsCommand extends Command {
     argParser.addFlag('clear',
         negatable: false,
         help: 'Clear log history before reading from logs (Android only).');
-    if (android == null) {
-      android = new AndroidDevice();
-    }
   }
 
   @override
   Future<int> run() async {
+    if (android == null) {
+      android = new AndroidDevice();
+    }
+
     Future<int> androidLogProcess = null;
     if (android.isConnected()) {
       androidLogProcess = android.logs(clear: argResults['clear']);

packages/flutter_tools/lib/src/start.dart

@@ -33,13 +33,14 @@ class StartCommand extends Command {
         defaultsTo: '.',
         abbr: 't',
         help: 'Target app path or filename to start.');
-    if (android == null) {
-      android = new AndroidDevice();
-    }
   }
 
   @override
   Future<int> run() async {
+    if (android == null) {
+      android = new AndroidDevice();
+    }
+
     bool startedSomewhere = false;
     bool poke = argResults['poke'];
     if (!poke) {

packages/flutter_tools/lib/src/stop.dart

@@ -18,14 +18,14 @@ class StopCommand extends Command {
   final description = 'Stop your Flutter app on all attached devices.';
   AndroidDevice android = null;
 
-  StopCommand([this.android]) {
+  StopCommand([this.android]);
+
+  @override
+  Future<int> run() async {
     if (android == null) {
       android = new AndroidDevice();
     }
-  }
 
-  @override
-  Future<int> run() async {
     if (stop()) {
       return 0;
     } else {

packages/flutter_tools/lib/src/trace.dart

@@ -27,13 +27,14 @@ class TraceCommand extends Command {
     argParser.addFlag('stop', negatable: false, help: 'Stop tracing.');
     argParser.addOption('duration',
         defaultsTo: '10', abbr: 'd', help: 'Duration in seconds to trace.');
-    if (android == null) {
-      android = new AndroidDevice();
-    }
   }
 
   @override
   Future<int> run() async {
+    if (android == null) {
+      android = new AndroidDevice();
+    }
+
     if (!android.isConnected()) {
       _logging.warning('No device connected, so no trace was completed.');
       return 1;