Fetch snippets from ChromeReader and show them on the NTP

chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsController.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsController.java
new file mode 100644
index 0000000000000000000000000000000000000000..55dd84cddfe5c06bf900d50b78db2903f04fc62e
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/snippets/SnippetsController.java
@@ -0,0 +1,59 @@
+// 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.chrome.browser.ntp.snippets;
+
+import android.content.Context;
+
+import org.chromium.base.ThreadUtils;
+import org.chromium.chrome.browser.profiles.Profile;
+import org.chromium.chrome.browser.signin.SigninManager;
+import org.chromium.chrome.browser.signin.SigninManager.SignInStateObserver;
+
+/**
+ * The main controller for calling into the native snippets component to fetch snippets
+ */
+public class SnippetsController implements SignInStateObserver {
+    private static SnippetsController sInstance;
+
+    private long mNativeSnippetsController;
+
+    public SnippetsController(Context applicationContext) {
+        SigninManager.get(applicationContext).addSignInStateObserver(this);
+    }
+
+    /**
+     * Fetches new snippets
+     *
+     * @param overwrite true if an update to the current snippets should be forced, and false if
+     * snippets should be downloaded only if there are no existing ones.
+     */
+    public void fetchSnippets(boolean overwrite) {
+        nativeFetchSnippets(Profile.getLastUsedProfile(), overwrite);
+    }
+
+    /**
+     * Retrieve the singleton instance of this class.
+     *
+     * @param context the current context.
+     * @return the singleton instance.
+     */
+    public static SnippetsController get(Context context) {
+        ThreadUtils.assertOnUiThread();
+        if (sInstance == null) {
+            sInstance = new SnippetsController(context.getApplicationContext());
+        }
+        return sInstance;
+    }
+
+    @Override
+    public void onSignedIn() {
+        fetchSnippets(true);
+    }
+
+    @Override
+    public void onSignedOut() {}
+
+    private native void nativeFetchSnippets(Profile profile, boolean overwrite);
+}