Reland of Generate Android .isolate files used for test()s

build/android/pylib/utils/isolator.py

Index: build/android/pylib/utils/isolator.py
diff --git a/build/android/pylib/utils/isolator.py b/build/android/pylib/utils/isolator.py
index 832b4ad3c301853d13555ecbaf0bc4b39e0a5bb1..2a044aa737c911815e1d6796dada0f47542d4c9a 100644
--- a/build/android/pylib/utils/isolator.py
+++ b/build/android/pylib/utils/isolator.py
@@ -55,6 +55,12 @@ def DefaultConfigVariables():
   }
 
 
+def IsIsolateEmpty(isolate_path):
+  """Returns whether there are no files in the .isolate."""
+  with open(isolate_path) as f:
+    return "'files': []" in f.read()
+
+
 class Isolator(object):
   """Manages calls to isolate.py for the android test runner scripts."""