[webnfc] Implement push method for Android nfc mojo service.

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

Index: content/public/android/java/src/org/chromium/content/browser/InterfaceRegistrar.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/InterfaceRegistrar.java b/content/public/android/java/src/org/chromium/content/browser/InterfaceRegistrar.java
index 1840a2dd4df075e1a9c72f243ddb8ce7795c9e5a..0bd9b5457963c99b05a896c79e56bfb823c5ef98 100644
--- a/content/public/android/java/src/org/chromium/content/browser/InterfaceRegistrar.java
+++ b/content/public/android/java/src/org/chromium/content/browser/InterfaceRegistrar.java
@@ -4,15 +4,20 @@
 
 package org.chromium.content.browser;
 
+import android.app.Activity;
 import android.content.Context;
 
 import org.chromium.base.annotations.CalledByNative;
 import org.chromium.base.annotations.JNINamespace;
 import org.chromium.content.browser.InterfaceRegistry.ImplementationFactory;
+import org.chromium.content_public.browser.WebContents;
 import org.chromium.device.battery.BatteryMonitorFactory;
+import org.chromium.device.nfc.NfcImpl;
 import org.chromium.device.vibration.VibrationManagerImpl;
 import org.chromium.mojom.device.BatteryMonitor;
 import org.chromium.mojom.device.VibrationManager;
+import org.chromium.mojom.device.nfc.Nfc;
+import org.chromium.ui.base.WindowAndroid;
 
 /**
  * Registers interfaces exposed by the browser in the given registry.
@@ -49,6 +54,54 @@ class InterfaceRegistrar {
         }
     }
 
+    private static class NfcImplementationFactory implements ImplementationFactory<Nfc> {
+        private final Context mContext;
+        private final WebContents mContents;
+
+        NfcImplementationFactory(Context context, WebContents contents) {
+            mContext = context;
+            mContents = contents;
+        }
+
+        private static class ContextAwareNfcImpl extends NfcImpl implements
+                WindowAndroidChangedObserver {
+            private final ContentViewCore mContextViewCore;
+
+            ContextAwareNfcImpl(Context context, ContentViewCore contextViewCore) {
+                super(context);
+                mContextViewCore = contextViewCore;
+                if (mContextViewCore != null) {
+                    mContextViewCore.addWindowAndroidChangedObserver(this);
+                    if (mContextViewCore.getWindowAndroid() != null) {
+                        setActivity(mContextViewCore.getWindowAndroid().getActivity().get());
+                    }
+                }
+            }
+
+            @Override
+            public void close() {
+                super.close();
+                if (mContextViewCore != null) {
+                    mContextViewCore.removeWindowAndroidChangedObserver(this);
+                }
+            }
+
+            @Override
+            public void onWindowAndroidChanged(WindowAndroid newWindowAndroid) {
+                Activity activity = null;
+                if (newWindowAndroid != null) {
+                    activity = newWindowAndroid.getActivity().get();
+                }
+                setActivity(activity);
+            }
+        }
+
+        @Override
+        public Nfc createImpl() {
+            return new ContextAwareNfcImpl(mContext, ContentViewCore.fromWebContents(mContents));
+        }
+    }
+
     @CalledByNative
     static void exposeInterfacesToRenderer(InterfaceRegistry registry, Context applicationContext) {
         assert applicationContext != null;
@@ -57,10 +110,13 @@ class InterfaceRegistrar {
     }
 
     @CalledByNative
-    static void exposeInterfacesToFrame(InterfaceRegistry registry, Context applicationContext) {
+    static void exposeInterfacesToFrame(InterfaceRegistry registry,
+            Context applicationContext, WebContents contents) {
         assert applicationContext != null;
         registry.addInterface(VibrationManager.MANAGER,
                 new VibrationManagerImplementationFactory(applicationContext));
+        registry.addInterface(Nfc.MANAGER,
+                new NfcImplementationFactory(applicationContext, contents));
         // TODO(avayvod): Register the PresentationService implementation here.
     }
 }