Expose a Java API for base/feature_list.h.

chrome/browser/android/chrome_feature_list.cc

Index: chrome/browser/android/chrome_feature_list.cc
diff --git a/chrome/browser/android/chrome_feature_list.cc b/chrome/browser/android/chrome_feature_list.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7a76be513adad756e961359d4017aa2ca19623e4
--- /dev/null
+++ b/chrome/browser/android/chrome_feature_list.cc
@@ -0,0 +1,51 @@
+// Copyright 2015 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 "chrome/browser/android/chrome_feature_list.h"
+
+#include <string>
+
+#include "base/android/jni_string.h"
+#include "base/feature_list.h"
+#include "jni/ChromeFeatureList_jni.h"
+
+using base::android::ConvertJavaStringToUTF8;
+
+namespace {
+
+const base::Feature kPhysicalWebFeature {
+  "PhysicalWeb", base::FEATURE_DISABLED_BY_DEFAULT
+};
+
+// Array of features exposed through the Java ChromeFeatureList API. Entries in
+// this array may either refer to features defined in this file (above) or in
+// other locations in the code base (e.g. chrome/, components/, etc).
+const base::Feature* kFeaturesExposedToJava[] = {
+    &kPhysicalWebFeature,
+};
+
+}  // namespace
+
+static jboolean IsEnabled(JNIEnv* env,

[nyquist, 2015/12/18 22:47:39]

Why is this not namespaces to chrome::android?

[Alexei Svitkine (slow), 2015/12/18 22:54:45]

I tried this originally, but seems the header definition generated in
ChromeFeatureList_jni.h wants it to be in the global namespace. Not sure if
there's some trick I'm missing?

[Alexei Svitkine (slow), 2015/12/18 23:06:59]

Looks like I was missing the @JNINamespace annotation. Done!

+                          const JavaParamRef<jclass>& clazz,
+                          const JavaParamRef<jstring>& jfeature_name) {
+  const std::string feature_name = ConvertJavaStringToUTF8(env, jfeature_name);
+  for (size_t i = 0; i < arraysize(kFeaturesExposedToJava); ++i) {
+    if (kFeaturesExposedToJava[i]->name == feature_name)
+      return base::FeatureList::IsEnabled(*kFeaturesExposedToJava[i]);
+  }
+  // Features queried via this API must be present in |kFeaturesExposedToJava|.
+  NOTREACHED();
+  return false;
+}
+
+namespace chrome {
+namespace android {
+
+bool RegisterChromeFeatureListJni(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace android
+}  // namespace chrome