android: add the ability to enable window display on the emulator

This would help local development with emulator

Bug: 922145
Change-Id: Ie107381b80e3c0acae1145cf4078a327e38ffa3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849434Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Haiyang Pan <hypan@google.com>
Cr-Commit-Position: refs/heads/master@{#704885}

build/android/pylib/local/emulator/avd.py

@@ -428,7 +428,7 @@ class _AvdInstance(object):
   def __str__(self):
     return '%s|%s' % (self._avd_name, (self._emulator_serial or id(self)))
 
-  def Start(self, read_only=True, snapshot_save=False):
+  def Start(self, read_only=True, snapshot_save=False, window=False):
     """Starts the emulator running an instance of the given AVD."""
     with tempfile_ext.TemporaryFileName() as socket_path, (contextlib.closing(
         socket.socket(socket.AF_UNIX))) as sock:
@@ -439,7 +439,6 @@ class _AvdInstance(object):
           self._avd_name,
           '-report-console',
           'unix:%s' % socket_path,
-          '-no-window',
       ]
       if read_only:
         emulator_cmd.append('-read-only')
@@ -448,6 +447,13 @@ class _AvdInstance(object):
       emulator_env = {}
       if self._emulator_home:
         emulator_env['ANDROID_EMULATOR_HOME'] = self._emulator_home
+      if window:
+        if 'DISPLAY' in os.environ:
+          emulator_env['DISPLAY'] = os.environ.get('DISPLAY')
+        else:
+          raise AvdException('Emulator failed to start: DISPLAY not defined')
+      else:
+        emulator_cmd.append('-no-window')
       sock.listen(1)
 
       logging.info('Starting emulator.')

build/android/pylib/local/emulator/local_emulator_environment.py

@@ -23,6 +23,7 @@ class LocalEmulatorEnvironment(local_device_environment.LocalDeviceEnvironment):
     elif args.emulator_count >= _MAX_ANDROID_EMULATORS:
       logging.warning('--emulator-count capped at 16.')
     self._emulator_count = min(_MAX_ANDROID_EMULATORS, args.emulator_count)
+    self._emulator_window = args.emulator_window
     self._emulator_instances = []
     self._device_serials = []
 
@@ -36,7 +37,7 @@ class LocalEmulatorEnvironment(local_device_environment.LocalDeviceEnvironment):
 
     def start_emulator_instance(e):
       try:
-        e.Start()
+        e.Start(window=self._emulator_window)
         return e
       except avd.AvdException:
         logging.exception('Failed to start emulator instance.')

build/android/test_runner.py

@@ -320,6 +320,11 @@ def AddEmulatorOptions(parser):
       type=int,
       default=1,
       help='Number of emulators to use.')
+  parser.add_argument(
+      '--emulator-window',
+      action='store_true',
+      default=False,
+      help='Enable graphical window display on the emulator.')
 
 
 def AddGTestOptions(parser):