Android GTest Runner: Don't clear app data for incremental installs

build/android/pylib/local/device/local_device_gtest_run.py

Index: build/android/pylib/local/device/local_device_gtest_run.py
diff --git a/build/android/pylib/local/device/local_device_gtest_run.py b/build/android/pylib/local/device/local_device_gtest_run.py
index caef0548d2daf93f7dc392449f7d935df0851632..675d191b4cdd58d8f9dbf413dd5eaa75687fc9a6 100644
--- a/build/android/pylib/local/device/local_device_gtest_run.py
+++ b/build/android/pylib/local/device/local_device_gtest_run.py
@@ -306,7 +306,10 @@ class LocalDeviceGtestRun(local_device_test_run.LocalDeviceTestRun):
     if self._test_instance.app_files:
       self._delegate.PullAppFiles(device, self._test_instance.app_files,
                                   self._test_instance.app_file_dir)
-    self._delegate.Clear(device)
+    # Clearing data when using incremental install wipes out cached optimized
+    # dex files (and shouldn't be necessary by tests anyways).
+    if not self._env.incremental_install:
+      self._delegate.Clear(device)
 
     # Parse the output.
     # TODO(jbudorick): Transition test scripts away from parsing stdout.