[Home] Add a Chrome Home specific incognito NTP

chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java
index ea7871d00a51d3cdf8d40aed4e1f7cac25e0de95..9b7e89ba9b6c3211252b4ff1a0e8c0142f7c6f6d 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheetContentController.java
@@ -6,6 +6,7 @@ package org.chromium.chrome.browser.widget.bottomsheet;
 
 import android.app.Activity;
 import android.content.Context;
+import android.content.res.ColorStateList;
 import android.content.res.Resources;
 import android.support.annotation.IntDef;
 import android.support.design.internal.BottomNavigationItemView;
@@ -18,6 +19,7 @@ import android.view.View;
 import android.view.ViewGroup;
 
 import org.chromium.base.ActivityState;
+import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ApplicationStatus.ActivityStateListener;
 import org.chromium.base.VisibleForTesting;
@@ -25,8 +27,11 @@ import org.chromium.chrome.R;
 import org.chromium.chrome.browser.bookmarks.BookmarkSheetContent;
 import org.chromium.chrome.browser.download.DownloadSheetContent;
 import org.chromium.chrome.browser.history.HistorySheetContent;
+import org.chromium.chrome.browser.ntp.IncognitoBottomSheetContent;
 import org.chromium.chrome.browser.snackbar.SnackbarManager;
 import org.chromium.chrome.browser.suggestions.SuggestionsBottomSheetContent;
+import org.chromium.chrome.browser.tabmodel.EmptyTabModelSelectorObserver;
+import org.chromium.chrome.browser.tabmodel.TabModel;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.chrome.browser.util.MathUtils;
 import org.chromium.chrome.browser.widget.bottomsheet.BottomSheet.BottomSheetContent;
@@ -53,8 +58,10 @@ public class BottomSheetContentController extends BottomNavigationView
     public static final int TYPE_DOWNLOADS = 1;
     public static final int TYPE_BOOKMARKS = 2;
     public static final int TYPE_HISTORY = 3;
+    public static final int TYPE_INCOGNITO_HOME = 4;
 
     private final Map<Integer, BottomSheetContent> mBottomSheetContents = new HashMap<>();
+    private BottomSheetContent mIncognitoHome;
 
     private final BottomSheetObserver mBottomSheetObserver = new EmptyBottomSheetObserver() {
         @Override
@@ -117,6 +124,16 @@ public class BottomSheetContentController extends BottomNavigationView
         mBottomSheet = bottomSheet;
         mBottomSheet.addObserver(mBottomSheetObserver);
         mTabModelSelector = tabModelSelector;
+        mTabModelSelector.addObserver(new EmptyTabModelSelectorObserver() {
+            @Override
+            public void onTabModelSelected(TabModel newModel, TabModel oldModel) {
+                updateVisuals(newModel.isIncognito());
+                showBottomSheetContent(R.id.action_home);
+
+                // Release incognito bottom sheet content so that it can be garbage collected.
+                if (!newModel.isIncognito()) mIncognitoHome = null;
+            }
+        });
 
         Resources res = getContext().getResources();
         mDistanceBelowToolbarPx = controlContainerHeight
@@ -178,6 +195,10 @@ public class BottomSheetContentController extends BottomNavigationView
     }
 
     private BottomSheetContent getSheetContentForId(int navItemId) {
+        if (mTabModelSelector.isIncognitoSelected() && navItemId == R.id.action_home) {

[mdjones, 2017/04/12 16:51:35]

Why is this special cased? Is the assumption that, since there's little content,
the user won't be returning?

[Theresa, 2017/04/12 21:32:03]

The map storing all of the other BottomSheetContent objects is keyed off from
navigation item id. R.id.action_home is overloaded (it can be
IncognitobottomSheetContent or SuggestionsBottomSheetContent). Instead of
introducing special code here, I could manipulate the navItemId used to get the
BottomSheetContent out of the map, but that seemed more complex.

[dgn, 2017/04/12 22:28:00]

why is introducing a special code a bad thing? According to
https://developer.android.com/reference/android/view/View.html#setId(int) Ids
are positive ints, so you could use -1 without risking conflicts? 

[Theresa, 2017/04/12 23:12:11]

Changing the id isn't a bad thing. The IncognitoBottomSheetContent has to be
handled separately regardless of whether it's in the map or stored as a separate
variable. Storing it as a separate variable introduces a branch in the code
here. Storing it in the map introduces an if statement to change the navItemId
here and another check in BottomSheetObserver#onSheetClosed() to avoid
destroying the IncognitoBottomSheetContent. I think both approaches are valid,
so I'm happy to put it in the map if you and Matt feel strongly about the
approach.

[mdjones, 2017/04/13 20:34:03]

I think we only need to special-case the suggestions content; the incognito view
is quite a bit smaller and can be created much more quickly. If you agree on
that point, I'd rather have the incognito view live in the map.

[Theresa, 2017/04/13 21:28:14]

Done.

When the bottom sheet is closed, this class resets the bottom sheet content to
R.id.action_home. In addition to showing the right content the next time the
panel is opened, that logic is needed to ensure the regular toolbar starts
showing again when the sheet is closed. I reworked the logic in onSheetClosed()
to support destroying the IncognitoBottomSheetContent in the map while still
ensuring that the regular toolbar is shown.

+            return getIncognitoHomeSheetContent();
+        }
+
         BottomSheetContent content = mBottomSheetContents.get(navItemId);
         if (content != null) return content;
 
@@ -199,6 +220,14 @@ public class BottomSheetContentController extends BottomNavigationView
         return content;
     }
 
+    private BottomSheetContent getIncognitoHomeSheetContent() {
+        if (mIncognitoHome == null) {
+            mIncognitoHome = new IncognitoBottomSheetContent(
+                    mTabModelSelector.getCurrentTab().getActivity());
+        }
+        return mIncognitoHome;
+    }
+
     private void showBottomSheetContent(int navItemId) {
         // There are some bugs related to programatically selecting menu items that are fixed in
         // newer support library versions.
@@ -210,6 +239,17 @@ public class BottomSheetContentController extends BottomNavigationView
         mBottomSheet.showContent(getSheetContentForId(mSelectedItemId));
     }
 
+    private void updateVisuals(boolean isIncognitoTabModelSelected) {
+        setBackgroundResource(isIncognitoTabModelSelected ? R.color.incognito_primary_color
+                                                          : R.color.appbar_background);
+
+        ColorStateList tint = ApiCompatibilityUtils.getColorStateList(getResources(),
+                isIncognitoTabModelSelected ? R.color.bottom_nav_tint_incognito
+                                            : R.color.bottom_nav_tint);
+        setItemIconTintList(tint);
+        setItemTextColor(tint);
+    }
+
     /**
      * @param itemId The id of the MenuItem to select.
      */