[NTP Snippets] Clear the snippets when the user signs out

chrome/browser/android/ntp/ntp_snippets_bridge.cc

 // 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.
 
 #include "chrome/browser/android/ntp/ntp_snippets_bridge.h"
 
 #include <jni.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_array.h"
@@ skipping 150 matching lines @@
       ToJavaArrayOfStrings(env, snippets).obj(),
       ToJavaLongArray(env, timestamps).obj(),
       ToJavaArrayOfStrings(env, publishers).obj());
 }
 
 void NTPSnippetsBridge::NTPSnippetsServiceShutdown() {
   observer_.Reset();
   snippet_service_observer_.Remove(ntp_snippets_service_);
 }
 
+void NTPSnippetsBridge::NTPSnippetsServiceCleared() {
+  // The user signed out or disabled sync. Since snippets rely on those, we
+  // clear them to be consistent with the initially signed out state.
+  JNIEnv* env = base::android::AttachCurrentThread();
+  Java_SnippetsBridge_onSnippetsCleared(env, observer_.obj());
+}
+
 void NTPSnippetsBridge::OnImageFetched(ScopedJavaGlobalRef<jobject> callback,
                                        const std::string& snippet_id,
                                        const SkBitmap* bitmap) {
   JNIEnv* env = AttachCurrentThread();
 
   ScopedJavaLocalRef<jobject> j_bitmap;
   if (bitmap && !bitmap->isNull())
     j_bitmap = gfx::ConvertToJavaBitmap(bitmap);
 
   Java_FetchSnippetImageCallback_onSnippetImageAvailable(env, callback.obj(),
                                                          j_bitmap.obj());
 }
 
 // static
 bool NTPSnippetsBridge::Register(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }