[Android] Create and use feature list for //components/external_intents

This CL eliminates the last //chrome dependence of
ExternalNavigationHandler.java, on ChromeFeatureList.java. To do so it
componentizes the one feature that ExternalNavigationHandler uses into
//components/external_intents via a minimal
ExternalIntentsFeatureList.java.

Bug: 1031465
Change-Id: If3c81a1d03516a4d71a98126c939255f74296616
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096559
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749130}

chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationHandler.java

@@ -26,9 +26,9 @@ import org.chromium.base.IntentUtils;
 import org.chromium.base.Log;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.metrics.RecordUserAction;
-import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.components.embedder_support.util.UrlConstants;
 import org.chromium.components.embedder_support.util.UrlUtilities;
+import org.chromium.components.external_intents.ExternalIntentsFeatureList;
 import org.chromium.components.external_intents.ExternalIntentsSwitches;
 import org.chromium.components.external_intents.ExternalNavigationParams;
 import org.chromium.components.external_intents.RedirectHandler;
@@ -361,8 +361,8 @@ public class ExternalNavigationHandler {
     /** Wrapper of check against the feature to support overriding for testing. */
     @VisibleForTesting
     boolean blockExternalFormRedirectsWithoutGesture() {
-        return ChromeFeatureList.isEnabled(
-                ChromeFeatureList.INTENT_BLOCK_EXTERNAL_FORM_REDIRECT_NO_GESTURE);
+        return ExternalIntentsFeatureList.isEnabled(
+                ExternalIntentsFeatureList.INTENT_BLOCK_EXTERNAL_FORM_REDIRECT_NO_GESTURE);
     }
 
     /**

chrome/browser/BUILD.gn

@@ -2999,6 +2999,7 @@ jumbo_static_library("browser") {
       "//components/crash/android:crash_android",
       "//components/embedder_support/android:util",
       "//components/embedder_support/android:web_contents_delegate",
+      "//components/external_intents/android",
       "//components/feed:buildflags",
       "//components/feed:feature_list",
       "//components/invalidation/impl:feature_list",

chrome/browser/DEPS

@@ -98,6 +98,7 @@ include_rules = [
   "+components/embedder_support",
   "+components/encrypted_messages",
   "+components/exo",
+  "+components/external_intents",
   "+components/favicon_base",
   "+components/favicon/content",
   "+components/favicon/core",

chrome/browser/about_flags.cc

@@ -177,6 +177,7 @@
 #if defined(OS_ANDROID)
 #include "chrome/browser/android/explore_sites/explore_sites_feature.h"
 #include "chrome/browser/flags/android/chrome_feature_list.h"
+#include "components/external_intents/android/external_intents_feature_list.h"
 #else  // OS_ANDROID
 #include "chrome/browser/media/router/media_router_feature.h"
 #endif  // OS_ANDROID
@@ -4861,7 +4862,7 @@ const FeatureEntry kFeatureEntries[] = {
      flag_descriptions::kIntentBlockExternalFormRedirectsNoGestureDescription,
      kOsAndroid,
      FEATURE_VALUE_TYPE(
-         chrome::android::kIntentBlockExternalFormRedirectsNoGesture)},
+         external_intents::kIntentBlockExternalFormRedirectsNoGesture)},
     {"recover-from-never-save-android",
      flag_descriptions::kRecoverFromNeverSaveAndroidName,
      flag_descriptions::kRecoverFromNeverSaveAndroidDescription, kOsAndroid,

chrome/browser/flags/android/chrome_feature_list.cc

@@ -157,7 +157,6 @@ const base::Feature* kFeaturesExposedToJava[] = {
     &kHorizontalTabSwitcherAndroid,
     &kImmersiveUiMode,
     &kInlineUpdateFlow,
-    &kIntentBlockExternalFormRedirectsNoGesture,
     &kKitKatSupported,
     &kNewPhotoPicker,
     &kNotificationSuspender,
@@ -458,10 +457,6 @@ const base::Feature kImmersiveUiMode{"ImmersiveUiMode",
 const base::Feature kInlineUpdateFlow{"InlineUpdateFlow",
                                       base::FEATURE_DISABLED_BY_DEFAULT};
 
-const base::Feature kIntentBlockExternalFormRedirectsNoGesture{
-    "IntentBlockExternalFormRedirectsNoGesture",
-    base::FEATURE_DISABLED_BY_DEFAULT};
-
 const base::Feature kKitKatSupported{"KitKatSupported",
                                      base::FEATURE_DISABLED_BY_DEFAULT};
 

chrome/browser/flags/android/chrome_feature_list.h

@@ -78,7 +78,6 @@ extern const base::Feature kHorizontalTabSwitcherAndroid;
 extern const base::Feature kImmersiveUiMode;
 extern const base::Feature kImprovedA2HS;
 extern const base::Feature kInlineUpdateFlow;
-extern const base::Feature kIntentBlockExternalFormRedirectsNoGesture;
 extern const base::Feature kKitKatSupported;
 extern const base::Feature kLanguagesPreference;
 extern const base::Feature kNewPhotoPicker;

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/ChromeFeatureList.java

@@ -310,8 +310,6 @@ public abstract class ChromeFeatureList {
             "ImprovedCookieControlsForThirdPartyCookieBlocking";
     public static final String INLINE_UPDATE_FLOW = "InlineUpdateFlow";
     public static final String INSTALLABLE_AMBIENT_BADGE_INFOBAR = "InstallableAmbientBadgeInfoBar";
-    public static final String INTENT_BLOCK_EXTERNAL_FORM_REDIRECT_NO_GESTURE =
-            "IntentBlockExternalFormRedirectsNoGesture";
     public static final String INTEREST_FEED_CONTENT_SUGGESTIONS = "InterestFeedContentSuggestions";
     public static final String INTEREST_FEED_FEEDBACK = "InterestFeedFeedback";
     public static final String KITKAT_SUPPORTED = "KitKatSupported";

components/external_intents/android/BUILD.gn

@@ -6,8 +6,31 @@ import("//build/config/android/rules.gni")
 
 android_library("java") {
   sources = [
+    "java/src/org/chromium/components/external_intents/ExternalIntentsFeatureList.java",
     "java/src/org/chromium/components/external_intents/ExternalIntentsSwitches.java",
     "java/src/org/chromium/components/external_intents/ExternalNavigationParams.java",
     "java/src/org/chromium/components/external_intents/RedirectHandler.java",
   ]
+
+  annotation_processor_deps = [ "//base/android/jni_generator:jni_processor" ]
+  deps = [
+    "//base:base_java",
+    "//base:jni_java",
+  ]
+}
+
+generate_jni("jni_headers") {
+  sources = [ "java/src/org/chromium/components/external_intents/ExternalIntentsFeatureList.java" ]
+}
+
+static_library("android") {
+  sources = [
+    "external_intents_feature_list.cc",
+    "external_intents_feature_list.h",
+  ]
+
+  deps = [
+    ":jni_headers",
+    "//base",
+  ]
 }

components/external_intents/android/external_intents_feature_list.cc

+// Copyright 2020 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 "components/external_intents/android/external_intents_feature_list.h"
+
+#include <jni.h>
+#include <stddef.h>
+#include <string>
+
+#include "base/android/jni_string.h"
+#include "components/external_intents/android/jni_headers/ExternalIntentsFeatureList_jni.h"
+
+namespace external_intents {
+
+namespace {
+
+// Array of features exposed through the Java ExternalIntentsFeatureList API.
+const base::Feature* kFeaturesExposedToJava[] = {
+    &kIntentBlockExternalFormRedirectsNoGesture,
+};
+
+const base::Feature* FindFeatureExposedToJava(const std::string& feature_name) {
+  for (const auto* feature : kFeaturesExposedToJava) {
+    if (feature->name == feature_name)
+      return feature;
+  }
+  NOTREACHED()
+      << "Queried feature cannot be found in ExternalIntentsFeatureList: "
+      << feature_name;
+  return nullptr;
+}
+
+}  // namespace
+
+// Alphabetical:
+const base::Feature kIntentBlockExternalFormRedirectsNoGesture{
+    "IntentBlockExternalFormRedirectsNoGesture",
+    base::FEATURE_DISABLED_BY_DEFAULT};
+
+static jboolean JNI_ExternalIntentsFeatureList_IsInitialized(JNIEnv* env) {
+  return !!base::FeatureList::GetInstance();
+}
+
+static jboolean JNI_ExternalIntentsFeatureList_IsEnabled(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jstring>& jfeature_name) {
+  const base::Feature* feature = FindFeatureExposedToJava(
+      base::android::ConvertJavaStringToUTF8(env, jfeature_name));
+  return base::FeatureList::IsEnabled(*feature);
+}
+
+}  // namespace external_intents

components/external_intents/android/external_intents_feature_list.h

+// Copyright 2020 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.
+
+#ifndef COMPONENTS_EXTERNAL_INTENTS_ANDROID_EXTERNAL_INTENTS_FEATURE_LIST_H_
+#define COMPONENTS_EXTERNAL_INTENTS_ANDROID_EXTERNAL_INTENTS_FEATURE_LIST_H_
+
+#include "base/feature_list.h"
+
+namespace external_intents {
+
+// Alphabetical:
+extern const base::Feature kIntentBlockExternalFormRedirectsNoGesture;
+
+}  // namespace external_intents
+
+#endif  // COMPONENTS_EXTERNAL_INTENTS_ANDROID_EXTERNAL_INTENTS_FEATURE_LIST_H_

components/external_intents/android/java/src/org/chromium/components/external_intents/ExternalIntentsFeatureList.java

+// Copyright 2020 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.components.external_intents;
+
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
+import org.chromium.base.annotations.NativeMethods;
+import org.chromium.base.library_loader.LibraryLoader;
+
+/**
+ * Java accessor for base/feature_list.h state.
+ *
+ * This class provides methods to access values of feature flags registered in
+ * |kFeaturesExposedToJava| in components/external_intents/android/external_intents_feature_list.cc.
+ *
+ */
+@JNINamespace("external_intents")
+@MainDex
+public abstract class ExternalIntentsFeatureList {
+    /** Prevent instantiation. */
+    private ExternalIntentsFeatureList() {}
+
+    /**
+     * @return Whether the native FeatureList is initialized or not.
+     */
+    private static boolean isNativeInitialized() {
+        if (!LibraryLoader.getInstance().isInitialized()) return false;
+        // Even if the native library is loaded, the C++ FeatureList might not be initialized yet.
+        // In that case, accessing it will not immediately fail, but instead cause a crash later
+        // when it is initialized. Return whether the native FeatureList has been initialized,
+        // so the return value can be tested, or asserted for a more actionable stack trace
+        // on failure.
+        //
+        // The FeatureList is however guaranteed to be initialized by the time
+        // AsyncInitializationActivity#finishNativeInitialization is called.
+        return ExternalIntentsFeatureListJni.get().isInitialized();
+    }
+
+    /**
+     * Returns whether the specified feature is enabled or not.
+     *
+     * Note: Features queried through this API must be added to the array
+     * |kFeaturesExposedToJava| in
+     * components/external_intents/android/external_intents_feature_list.cc.
+     *
+     * Calling this has the side effect of bucketing this client, which may cause an experiment to
+     * be marked as active.
+     *
+     * Should be called only after native is loaded.
+     *
+     * @param featureName The name of the feature to query.
+     * @return Whether the feature is enabled or not.
+     */
+    public static boolean isEnabled(String featureName) {
+        assert isNativeInitialized();
+        return ExternalIntentsFeatureListJni.get().isEnabled(featureName);
+    }
+
+    /** Alphabetical: */
+    public static final String INTENT_BLOCK_EXTERNAL_FORM_REDIRECT_NO_GESTURE =
+            "IntentBlockExternalFormRedirectsNoGesture";
+
+    @NativeMethods
+    interface Natives {
+        boolean isInitialized();
+        boolean isEnabled(String featureName);
+    }
+}