Add swipe-to-dismiss notifications in popup menu.

- Next secondary icon animates up to replace dismissed main notification
- Add padding around main notification so it always aligns with the
  straight edges of the view (not the rounded corners); looks more
  dismissable
- Notification view collapses as notifications are dismissed
- To mimic system notification behavior, we copy SwipeHelper,
  FlingAnimationUtils, and Interpolators. We also apply elevation
  to notifications and reveal a darker color beneath when dismissing.

Bug: 32410600
Change-Id: I9fbf10e73bb4996f17ef061c856efb013967d972

src/com/android/launcher3/FastBitmapDrawable.java

@@ -129,10 +129,7 @@ public class FastBitmapDrawable extends Drawable {
         mBadgeInfo = badgeInfo;
         mBadgeRenderer = badgeRenderer;
         if (wasBadged || isBadged) {
-            if (mBadgeInfo != null && mIconPalette == null) {
-                mIconPalette = IconPalette.fromDominantColor(Utilities
-                        .findDominantColorByHue(mBitmap, 20));
-            }
+            mIconPalette = getIconPalette();
             invalidateSelf();
         }
     }
@@ -161,6 +158,14 @@ public class FastBitmapDrawable extends Drawable {
         }
     }
 
+    public IconPalette getIconPalette() {
+        if (mIconPalette == null) {
+            mIconPalette = IconPalette.fromDominantColor(Utilities
+                    .findDominantColorByHue(mBitmap, 20));
+        }
+        return mIconPalette;
+    }
+
     private boolean hasBadge() {
         return mBadgeInfo != null && mBadgeInfo.getNotificationCount() != 0;
     }