[Android] Trigger native event batching through Feature API

content/browser/android/content_feature_list.cc

+// Copyright 2017 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.
+
+#include "content/browser/android/content_feature_list.h"
+
+#include "base/android/jni_string.h"
+#include "base/feature_list.h"
+#include "base/macros.h"
+#include "jni/ContentFeatureList_jni.h"
+
+using base::android::ConvertJavaStringToUTF8;
+using base::android::JavaParamRef;
+
+namespace content {
+namespace android {
+
+namespace {
+
+// Array of features exposed through the Java ContentFeatureList API. Entries in
+// this array may either refer to features defined in the header of this file or
+// in other locations in the code base (e.g. chrome/, components/, etc).

[Ilya Sherman, 2017/03/16 03:39:49]

nit: Probably not in chrome/ nor components/ ;-)

[chongz, 2017/03/16 16:12:21]

Done.

+const base::Feature* kFeaturesExposedToJava[] = {
+    &kRequestUnbufferedDispatch,
+};
+
+const base::Feature* FindFeatureExposedToJava(const std::string& feature_name) {
+  for (size_t i = 0; i < arraysize(kFeaturesExposedToJava); ++i) {
+    if (kFeaturesExposedToJava[i]->name == feature_name)
+      return kFeaturesExposedToJava[i];
+  }
+  NOTREACHED() << "Features queried via ContentFeatureList must be present in "
+                  "|kFeaturesExposedToJava|.";

[Ilya Sherman, 2017/03/16 03:39:49]

nit: Could you please move this string into a comment?  There's no need to
compile it into the binary.  Alternately, we could make this message more useful
by printing the name of the queried feature that isn't present in the list.

[chongz, 2017/03/16 16:12:21]

Done.

+  return nullptr;
+}
+
+}  // namespace
+
+// Alphabetical:
+const base::Feature kRequestUnbufferedDispatch{
+    "RequestUnbufferedDispatch", base::FEATURE_DISABLED_BY_DEFAULT};
+
+static jboolean IsEnabled(JNIEnv* env,
+                          const JavaParamRef<jclass>& clazz,
+                          const JavaParamRef<jstring>& jfeature_name) {
+  const base::Feature* feature =
+      FindFeatureExposedToJava(ConvertJavaStringToUTF8(env, jfeature_name));
+  return base::FeatureList::IsEnabled(*feature);
+}
+
+bool RegisterContentFeatureListJni(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace android
+}  // namespace content