📰 Add visibility change triggers for bottom sheet content

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

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java
index 48602af38b47d2ece5e6084edd9c66138dda557a..d56158733ce8361e69ffcb213a79f9d5866e06d0 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/bottomsheet/BottomSheet.java
@@ -9,6 +9,7 @@
 import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator;
+import android.app.Activity;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.graphics.Color;
@@ -27,11 +28,15 @@
 import android.view.animation.Interpolator;
 import android.widget.FrameLayout;
 
+import org.chromium.base.ActivityState;
+import org.chromium.base.ActivityState.ActivityStateEnum;
 import org.chromium.base.ApiCompatibilityUtils;
+import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.ObserverList;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.R;
+import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.NativePageHost;
 import org.chromium.chrome.browser.TabLoadStatus;
 import org.chromium.chrome.browser.firstrun.FirstRunStatus;
@@ -353,6 +358,20 @@ public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float ve
         }
     }
 
+    /** Returns whether the bottom sheet is in a stable state, not transitioning or animating. */

[mdjones, 2017/05/05 15:52:00]

Full javadoc please.

[dgn, 2017/05/09 16:55:51]

Done.

+    public static boolean isStateStable(@SheetState int sheetState) {
+        switch (sheetState) {
+            case SHEET_STATE_PEEK:
+            case SHEET_STATE_HALF:
+            case SHEET_STATE_FULL:
+                return true;
+            case SHEET_STATE_NONE:

[mdjones, 2017/05/05 15:52:00]

SHEET_STATE_NONE is a private member that is used for internal state management.
I'd rather this not be handled here as it implies external knowledge of the
variable. Instead, I'd have an assert at the top to make sure the input is not
that.

[dgn, 2017/05/09 16:55:51]

Added an assert here, as otherwise the linter complains about unhandled enum
value.

+            case SHEET_STATE_SCROLLING:
+            default:
+                return false;
+        }
+    }
+
     /**
      * Constructor for inflation from XML.
      * @param context An Android context.
@@ -518,8 +537,9 @@ private boolean isToolbarAndroidViewHidden() {
      * calculations in this class.
      * @param root The container of the bottom sheet.
      * @param controlContainer The container for the toolbar.
+     * @param chromeActivity The activity in which this bottom bar is contained.
      */
-    public void init(View root, View controlContainer) {
+    public void init(View root, View controlContainer, final ChromeActivity chromeActivity) {
         mControlContainer = controlContainer;
         mToolbarHeight = mControlContainer.getHeight();
 
@@ -569,6 +589,29 @@ public void onLayoutChange(View v, int left, int top, int right, int bottom,
             }
         });
 
+        ApplicationStatus.registerStateListenerForActivity(

[mdjones, 2017/05/05 15:52:00]

I'd rather see this logic attached to the SuggestionsBottomSheetContent
(BottomSheetContentController has access to ChromeActivity). My reasoning is
that this is an event on the activity and not the sheet; this seems like an
unnecessary layer for the single use it has.

[dgn, 2017/05/09 16:55:51]

Done.

+                new ApplicationStatus.ActivityStateListener() {
+                    @Override
+                    public void onActivityStateChange(
+                            Activity activity, @ActivityStateEnum int newState) {
+                        assert chromeActivity == activity;
+
+                        if (newState == ActivityState.DESTROYED) {
+                            ApplicationStatus.unregisterActivityStateListener(this);
+                            return;
+                        }
+
+                        if (!mIsSheetOpen) return;
+
+                        if (newState == ActivityState.RESUMED) {
+                            onSheetForegrounded();
+                        } else if (newState == ActivityState.PAUSED) {
+                            onSheetBackgrounded();
+                        }
+                    }
+                },
+                chromeActivity);
+
         mPlaceholder = new View(getContext());
         LayoutParams placeHolderParams =
                 new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
@@ -789,6 +832,20 @@ private void onSheetClosed() {
     }
 
     /**
+     * A notification that the sheet was revealed by putting the app in the foreground.
+     */
+    private void onSheetForegrounded() {
+        for (BottomSheetObserver o : mObservers) o.onSheetForegrounded();
+    }
+
+    /**
+     * A notification that the sheet was hidden by putting the app in the background.
+     */
+    private void onSheetBackgrounded() {
+        for (BottomSheetObserver o : mObservers) o.onSheetBackgrounded();
+    }
+
+    /**
      * Creates an unadjusted version of a MotionEvent.
      * @param e The original event.
      * @return The unadjusted version of the event.