Make combined native/manual JNI registration work for clang.

build/jni_generator.gypi

Index: build/jni_generator.gypi
diff --git a/build/jni_generator.gypi b/build/jni_generator.gypi
index 853b5f6e789bf11fc3b9310a6bb7cc2da12a6ad0..c2c71e763cf23666465a229a9f89ebaa93182b7e 100644
--- a/build/jni_generator.gypi
+++ b/build/jni_generator.gypi
@@ -36,7 +36,7 @@
     'jni_generator_includes%': (
         'base/android/jni_generator/jni_generator_helper.h'
     ),
-    'native_exports%': '',
+    'native_exports%': '--native_exports_optional',
   },
   'rules': [
     {
@@ -92,14 +92,6 @@
         '<(DEPTH)/build/android/android_exports.gyp:android_exports',
       ],
     }],
-    ['clang==0', {
-      # Clang builds currently fail with --native_exports_optional due to
-      # http://llvm.org/bugs/show_bug.cgi?id=22602 - only enable for gcc.
-      # http://crbug.com/442327
-      'variables': {
-        'native_exports%': '--native_exports_optional',
-      },
-    }],
   ],
 }