Use HTTP response headers for PNaCl caching instead of bitcode hash.

ppapi/ppapi_tests.gypi

Index: ppapi/ppapi_tests.gypi
diff --git a/ppapi/ppapi_tests.gypi b/ppapi/ppapi_tests.gypi
index 28961575b7f55d312d670f21982d876d7365b49d..d434f8a37e273026d47737a41e181e1f586ce1fc 100644
--- a/ppapi/ppapi_tests.gypi
+++ b/ppapi/ppapi_tests.gypi
@@ -152,10 +152,23 @@
         '../testing/gtest.gyp:gtest',
         '../ui/surface/surface.gyp:surface',
       ],
+      # For the nacl_http_response_headers_unittest below.
+      'include_dirs': [
+        '../ppapi',
+      ],
       'sources': [
         'proxy/run_all_unittests.cc',
 
         'host/resource_message_filter_unittest.cc',
+        # Piggy back on ppapi_unittests for a simple NaCl unittest,
+        # which must not have dependencies on anything other than stdlibs.
+        # We add the source file, not just the test to ensure that the object
+        # is built.  Otherwise, we would need to depend on the NaCl trusted
+        # plugin being built to build the object.
+        # TODO(jvoung): move this to unit_tests instead of ppapi_unittests
+        # once this moves into chrome.
+        'native_client/src/trusted/plugin/nacl_http_response_headers.cc',
+        'native_client/src/trusted/plugin/nacl_http_response_headers_unittest.cc',
         'proxy/device_enumeration_resource_helper_unittest.cc',
         'proxy/file_chooser_resource_unittest.cc',
         'proxy/flash_resource_unittest.cc',