Use combined native/manual JNI registration.

build/config/android/rules.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//base/android/linker/config.gni")
 import("//build/config/android/config.gni")
 import("//build/config/android/internal_rules.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/relocation_packer/config.gni")
 
@@ skipping 56 matching lines @@
       rebase_path(jni_output_dir, root_build_dir),
       "--includes",
       rebase_path(jni_generator_include, "//"),
     ]
     if (defined(invoker.jni_generator_jarjar_file)) {
       args += [
         "--jarjar",
         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}") {
     # TODO(cjhopman): #includes should probably all be relative to
     # base_output_dir. Remove that from this config once the includes are
     # updated.
     include_dirs = [
       base_output_dir,
       package_output_dir,
     ]
@@ skipping 90 matching lines @@
         rebase_path(jar_file, root_build_dir),
         "--input_file",
         class,
         "--optimize_generation=1",
         "--ptr_type=long",
         "--output_dir",
         rebase_path(jni_output_dir, root_build_dir),
         "--includes",
         rebase_path(jni_generator_include, 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}") {
     include_dirs = [ base_output_dir ]
   }
 
   group(target_name) {
     deps = jni_actions
     if (defined(invoker.deps)) {
@@ skipping 1538 matching lines @@
 template("uiautomator_test") {
   set_sources_assignment_filter([])
   if (defined(invoker.testonly)) {
     testonly = invoker.testonly
   }
   assert(target_name != "")
   assert(invoker.deps != [] || true)
   group(target_name) {
   }
 }