Make combined native/manual JNI registration work for clang.

build/config/android/rules.gni

Index: build/config/android/rules.gni
diff --git a/build/config/android/rules.gni b/build/config/android/rules.gni
index 8ca064248e268036fbc7c1bc9231cca055da7fa0..c31b1d98e5799759091fa1021195acd79886b681 100644
--- a/build/config/android/rules.gni
+++ b/build/config/android/rules.gni
@@ -67,6 +67,7 @@ template("generate_jni") {
       rebase_path(jni_output_dir, root_build_dir),
       "--includes",
       rebase_path(jni_generator_include, "//"),
+      "--native_exports_optional",
     ]
     if (defined(invoker.jni_generator_jarjar_file)) {
       args += [
@@ -74,12 +75,6 @@ template("generate_jni") {
         rebase_path(jni_generator_jarjar_file, root_build_dir),
       ]
     }
-    if (!is_clang) {
-      # 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
-      args += [ "--native_exports_optional" ]
-    }
   }
 
   config("jni_includes_${target_name}") {
@@ -189,13 +184,8 @@ template("generate_jar_jni") {
         rebase_path(jni_output_dir, root_build_dir),
         "--includes",
         rebase_path(jni_generator_include, root_build_dir),
+        "--native_exports_optional",
       ]
-      if (!is_clang) {
-        # 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
-        args += [ "--native_exports_optional" ]
-      }
     }
   }