Added a UI for the Interests Prototype.

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
index 6cb1f91b21014de41ba51ae07b81e1ddb8ffc665..2e5c9e3035cead8c6c9d891d17293fe1d8ea1407 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageView.java
@@ -134,6 +134,9 @@ public class NewTabPageView extends FrameLayout
         /** Opens a given URL in the current tab. */
         void open(String url);
 
+        /** Opens the recent tabs page in the current tab. */
+        void navigateToInterests();
+
         /**
          * Animates the search box up into the omnibox and bring up the keyboard.
          * @param beginVoiceSearch Whether to begin a voice search.
@@ -307,6 +310,12 @@ public class NewTabPageView extends FrameLayout
                 mManager.navigateToBookmarks();
             }
         });
+        toolbar.getInterestsButton().setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mManager.navigateToInterests();
+            }
+        });
 
         initializeSearchBoxScrollHandling();
         addOnLayoutChangeListener(this);
@@ -325,6 +334,11 @@ public class NewTabPageView extends FrameLayout
             mSnippetsView.setLayoutManager(new LinearLayoutManager(getContext()));
             mSnippetsManager = new SnippetsManager(mManager, mSnippetsView);
         }
+
+        // Set up interests
+        if (CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_NTP_INTERESTS)) {

[knn, 2015/12/02 14:18:59]

Can we check if user is signed in here?

[PEConn, 2015/12/08 17:27:50]

Done.

+            toolbar.getInterestsButton().setVisibility(View.VISIBLE);
+        }
     }
 
     private int getTabsMovedIllustration() {