[Android] Trigger native event batching through Feature API

content/public/android/java/src/org/chromium/content/browser/ContentFeatureList.java

+// 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.
+
+package org.chromium.content.browser;
+
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
+
+/**
+ * Java accessor for base/feature_list.h state.
+ */
+@JNINamespace("content::android")
+@MainDex
+public class ContentFeatureList {

[Ilya Sherman, 2017/03/16 17:38:53]

Hmm, why did you remove "abstract" here?  Should it be removed from
ChromeFeatureList as well?

[chongz, 2017/03/16 18:54:04]

I'm not an expert on Java but I don't feel that we should have "abstract" here
as it doesn't have any abstract methods. Also I compared with some of other
classes with JNI bindings (e.g. ImeAdapter.java) and they don't have "abstract".

https://cs.chromium.org/chromium/src/content/public/android/java/src/org/chro...

I've removed "abstract" from ChromeFeatureList as well.

[Ilya Sherman, 2017/03/16 18:59:12]

Okay.  I suspect it was to help ensure that nobody tried to instantiate the
class, but I suppose the private constructor accomplishes that too.

[chongz, 2017/03/16 19:16:54]

Oh I see, that sounds reasonable. Anyway I've added back both "abstract" to
maintain the original style. 

+    // Prevent instantiation.
+    private ContentFeatureList() {}
+
+    /**
+     * Returns whether the specified feature is enabled or not.
+     *
+     * Note: Features queried through this API must be added to the array
+     * |kFeaturesExposedToJava| in content/browser/android/content_feature_list.cc
+     *
+     * @param featureName The name of the feature to query.
+     * @return Whether the feature is enabled or not.
+     */
+    public static boolean isEnabled(String featureName) {
+        return nativeIsEnabled(featureName);
+    }
+
+    // Alphabetical:
+    public static final String REQUEST_UNBUFFERED_DISPATCH = "RequestUnbufferedDispatch";
+
+    private static native boolean nativeIsEnabled(String featureName);
+}