Add a snapshot of flutter/engine/src/build to our sdk

build/android/pylib/perf/cache_control.py

Index: build/android/pylib/perf/cache_control.py
diff --git a/build/android/pylib/perf/cache_control.py b/build/android/pylib/perf/cache_control.py
new file mode 100644
index 0000000000000000000000000000000000000000..8065cf9ad7930a555f1c3866fb2f49b78c1e8e70
--- /dev/null
+++ b/build/android/pylib/perf/cache_control.py
@@ -0,0 +1,21 @@
+# Copyright 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+from pylib import android_commands
+from pylib.device import device_utils
+
+class CacheControl(object):
+  _DROP_CACHES = '/proc/sys/vm/drop_caches'
+
+  def __init__(self, device):
+    # TODO(jbudorick) Remove once telemetry gets switched over.
+    if isinstance(device, android_commands.AndroidCommands):
+      device = device_utils.DeviceUtils(device)
+    self._device = device
+
+  def DropRamCaches(self):
+    """Drops the filesystem ram caches for performance testing."""
+    self._device.RunShellCommand('sync', as_root=True)
+    self._device.WriteFile(CacheControl._DROP_CACHES, '3', as_root=True)
+