Tighten up a bunch of types in test.dart.

tools/testing/dart/android.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library android;
 
 import "dart:async";
 import "dart:convert" show LineSplitter, UTF8;
 import "dart:core";
 import "dart:collection";
@@ skipping 127 matching lines @@
     });
     getLines(_emulatorProcess.stderr).listen((line) {
       log("stderr: ${line.trim()}");
     });
     _emulatorProcess.exitCode.then((exitCode) {
       log("emulator exited with exitCode: $exitCode.");
     });
   }
 
   Future<bool> kill() {
-    var completer = new Completer();
+    var completer = new Completer<bool>();
     if (_emulatorProcess.kill()) {
       _emulatorProcess.exitCode.then((exitCode) {
         // TODO: Should we use exitCode to do something clever?
         completer.complete(true);
       });
     } else {
       log("Sending kill signal to emulator process failed");
       completer.complete(false);
     }
     return completer.future;
@@ skipping 43 matching lines @@
    * Blocks execution until the device is online
    */
   Future waitForDevice() {
     return _adbCommand(['wait-for-device']);
   }
 
   /**
    * Polls the 'sys.boot_completed' property. Returns as soon as the property is
    * 1.
    */
-  Future waitForBootCompleted() async {
+  Future<Null> waitForBootCompleted() async {
     while (true) {
       try {
         AdbCommandResult result =
             await _adbCommand(['shell', 'getprop', 'sys.boot_completed']);
         if (result.stdout.trim() == '1') return;
       } catch (_) {}
-      await new Future.delayed(const Duration(seconds: 2));
+      await new Future<Null>.delayed(const Duration(seconds: 2));
     }
   }
 
   /**
    * Put adb in root mode.
    */
-  Future adbRoot() {
-    var adbRootCompleter = new Completer();
+  Future<bool> adbRoot() {
+    var adbRootCompleter = new Completer<bool>();
     _adbCommand(['root']).then((_) {
       // TODO: Figure out a way to wait until the adb daemon was restarted in
       // 'root mode' on the device.
       new Timer(_adbServerStartupTime, () => adbRootCompleter.complete(true));
     }).catchError((error) => adbRootCompleter.completeError(error));
     return adbRootCompleter.future;
   }
 
   /**
    * Download data form the device.
@@ skipping 190 matching lines @@
           'Please make sure "adb devices" shows your device!');
     }
     print("Found ${devices.length} Android devices.");
     return new AdbDevicePool(devices);
   }
 
   Future<AdbDevice> acquireDevice() async {
     if (_idleDevices.length > 0) {
       return _idleDevices.removeFirst();
     } else {
-      var completer = new Completer();
+      var completer = new Completer<AdbDevice>();
       _waiter.add(completer);
       return completer.future;
     }
   }
 
   void releaseDevice(AdbDevice device) {
     if (_waiter.length > 0) {
       Completer completer = _waiter.removeFirst();
       completer.complete(device);
     } else {
       _idleDevices.add(device);
     }
   }
 }