[Android] emma_instr.py now removes any stale *.em/*sources.txt

third_party/cacheinvalidation/cacheinvalidation.gyp

Index: third_party/cacheinvalidation/cacheinvalidation.gyp
diff --git a/third_party/cacheinvalidation/cacheinvalidation.gyp b/third_party/cacheinvalidation/cacheinvalidation.gyp
index 166dbefd6802001f8eb8d815ef56cbcbfbb1b527..5a38bb2d6934c667eaf16e9d0c2d5f4c4b3d5936 100644
--- a/third_party/cacheinvalidation/cacheinvalidation.gyp
+++ b/third_party/cacheinvalidation/cacheinvalidation.gyp
@@ -7,7 +7,6 @@
     # This library should build cleanly with the extra warnings turned on
     # for Chromium.
     'chromium_code': 1,
-    'emma_never_instrument': 1,
   },
   'targets': [
     # The C++ files generated from the cache invalidation protocol buffers.
@@ -179,6 +178,9 @@
       ],
     }],
     ['OS == "android"', {
+      'variables': {
+        'emma_never_instrument': 1,
+      },
       'targets': [
         {
           'target_name': 'cacheinvalidation_proto_java',