Add global and per-WebContents java InterfaceRegistries.

content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.java

Index: content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.java
diff --git a/content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.java b/content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.java
new file mode 100644
index 0000000000000000000000000000000000000000..e76061d3574a41136d57a5fe590b18fe58e64c69
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.java
@@ -0,0 +1,74 @@
+// Copyright 2016 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_public.browser;
+
+import android.content.Context;
+
+import org.chromium.services.shell.InterfaceRegistry;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * A registrar for mojo interface implementations to provide to an InterfaceRegistry.
+ *
+ * @param <ParamType> the type of parameter to pass to the InterfaceRegistrar when adding its
+ *     interfaces to an InterfaceRegistry
+ */
+public interface InterfaceRegistrar<ParamType> {
+    /** Invoked to register interfaces on |registry|, parametrized by |paramValue|. */
+    public void registerInterfaces(InterfaceRegistry registry, ParamType paramValue);
+
+    /** A registry of InterfaceRegistrars. */
+    public static class Registry<ParamType> {
+        private static Registry<Context> sContextRegistry = null;
+        private static Registry<WebContents> sWebContentsRegistry = null;
+
+        private List<InterfaceRegistrar<ParamType>> mRegistrars =
+                new ArrayList<InterfaceRegistrar<ParamType>>();
+
+        public static void applyContextRegistrars(
+                InterfaceRegistry interfaceRegistry, Context context) {
+            if (sContextRegistry == null) {
+                return;
+            }
+            sContextRegistry.applyRegistrars(interfaceRegistry, context);
+        }
+
+        public static void applyWebContentsRegistrars(
+                InterfaceRegistry interfaceRegistry, WebContents webContents) {
+            if (sWebContentsRegistry == null) {
+                return;
+            }
+            sWebContentsRegistry.applyRegistrars(interfaceRegistry, webContents);
+        }
+
+        public static void addContextRegistrar(InterfaceRegistrar<Context> registrar) {
+            if (sContextRegistry == null) {
+                sContextRegistry = new Registry<Context>();
+            }
+            sContextRegistry.addRegistrar(registrar);
+        }
+
+        public static void addWebContentsRegistrar(InterfaceRegistrar<WebContents> registrar) {
+            if (sWebContentsRegistry == null) {
+                sWebContentsRegistry = new Registry<WebContents>();
+            }
+            sWebContentsRegistry.addRegistrar(registrar);
+        }
+
+        private Registry() {}
+
+        private void addRegistrar(InterfaceRegistrar<ParamType> registrar) {
+            mRegistrars.add(registrar);
+        }
+
+        private void applyRegistrars(InterfaceRegistry interfaceRegistry, ParamType param) {
+            for (InterfaceRegistrar<ParamType> registrar : mRegistrars) {
+                registrar.registerInterfaces(interfaceRegistry, param);
+            }
+        }
+    }
+}