Fade in notifications on wakeup.

We will be adding better expansion/translation animations here, but this is better than the current state of things, where notifs just suddenly appear.

Bug: 181020504
Test: manual
Change-Id: Ic350c6b59077d717b23d21ed5dff9f6f7301a658

packages/SystemUI/src/com/android/systemui/statusbar/NotificationShelf.java

@@ -173,7 +173,7 @@ public class NotificationShelf extends ActivatableNotificationView implements
                     getFullyClosedTranslation());
             viewState.zTranslation = ambientState.getBaseZHeight();
             viewState.clipTopAmount = 0;
-            viewState.alpha = 1;
+            viewState.alpha = 1f - ambientState.getHideAmount();
             viewState.belowSpeedBump = mHostLayoutController.getSpeedBumpIndex() == 0;
             viewState.hideSensitive = false;
             viewState.xTranslation = getTranslationX();

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/NotificationStackScrollLayout.java

@@ -1245,7 +1245,7 @@ public class NotificationStackScrollLayout extends ViewGroup implements Dumpable
         }
 
         if (mAmbientState.isHiddenAtAll()) {
-            clipToOutline = true;
+            clipToOutline = false;
             invalidateOutline();
             if (isFullyHidden()) {
                 setClipBounds(null);

packages/SystemUI/src/com/android/systemui/statusbar/notification/stack/StackScrollAlgorithm.java

@@ -320,6 +320,7 @@ public class StackScrollAlgorithm {
         }
         int childHeight = getMaxAllowedChildHeight(child);
         childViewState.yTranslation = currentYPosition;
+        childViewState.alpha = 1f - ambientState.getHideAmount();
 
         boolean isFooterView = child instanceof FooterView;
         boolean isEmptyShadeView = child instanceof EmptyShadeView;