Take screenshots using /system/bin/screencap instead of monkeyrunner.

build/android/pylib/android_commands.py

Index: build/android/pylib/android_commands.py
diff --git a/build/android/pylib/android_commands.py b/build/android/pylib/android_commands.py
index c40870e40137971d8f3330ed66eddb7d9c1b4464..e03632821322608f75afeff4fa1ddf80e8b77ad2 100644
--- a/build/android/pylib/android_commands.py
+++ b/build/android/pylib/android_commands.py
@@ -1066,6 +1066,17 @@ class AndroidCommands(object):
 
       return False
 
+  def TakeScreenshot(self, host_file):
+    """Saves a screenshot image to |host_file| on the host.
+
+    Args:
+      host_file: Absolute path to the image file to store on the host.
+    """
+    device_file = '%s/screenshot.png' % self.GetExternalStorage()
+    self.RunShellCommand('/system/bin/screencap -p %s' % device_file)
+    assert self._adb.Pull(device_file, host_file)
+    assert os.path.exists(host_file)
+
 
 class NewLineNormalizer(object):
   """A file-like object to normalize EOLs to '\n'.