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..3eccc7192eb2d2be7d2c49497e59d77ddfb386e3 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
@@ -51,6 +51,7 @@ import org.chromium.chrome.browser.profiles.MostVisitedSites.MostVisitedURLsObse
 import org.chromium.chrome.browser.profiles.MostVisitedSites.ThumbnailCallback;
 import org.chromium.chrome.browser.util.ViewUtils;
 import org.chromium.chrome.browser.widget.RoundedIconGenerator;
+import org.chromium.sync.signin.ChromeSigninController;
 import org.chromium.ui.text.SpanApplier;
 import org.chromium.ui.text.SpanApplier.SpanInfo;
 
@@ -134,6 +135,9 @@ 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. */

[newt (away), 2015/12/12 00:30:31]

fix javadoc

[PEConn, 2015/12/14 17:05:16]

Done.

+        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 +311,12 @@ 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 +335,12 @@ 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)
+                && ChromeSigninController.get(getContext()).isSignedIn()) {

[newt (away), 2015/12/12 00:30:31]

This class (NewTabPageView) shouldn't interact directly with other parts of
Chrome, such as the ChromeSigninController. That interaction should go through
NewTabPageManager.

Also, hiding/showing this button depending on the signed-in state probably isn't
a suitable long-term plan. Rather, we'd probably want a UI where the interests
page shows a sign-in promo if the user isn't already signed in. For now, this is
fine though.

[PEConn, 2015/12/14 17:05:16]

Done.

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