SystemUI: Add dual-tone light and dark themes for QS

Google's dual-tone QS design where the notification panel has a
semantically higher elevation adds depth to the notification+QS shade,
and we don't necessarily have to give it up just because our QS has
light and dark themes.

To preserve the dual-tone effect, use a darker background color for the
QS section:

Light:
    Notifications: neutral1 20 (surface_light)
    Notification panel: neutral1 50 (light BG)
    QS background: neutral1 100 (darker light BG / surface_header_light)
    Inactive QS tiles: neutral1 20 (surface_light)

Dark:
    Notifications: neutral1 800 (surface_dark)
    Notification panel: neutral1 900 (dark BG)
    QS background: neutral1 950 (surface_header_dark_sysui modulated to L* 5)
    Inactive QS tiles: neutral1 800 (surface_dark)

The dark QS background could be neutral1 0 (black) like it was before,
but I don't think it looks as good because it can't be tinted based on
the active wallpaper and thus stands out from other colors.

Unfortunately, Google's current CAM16-based modulation causes hue shifts
in extreme light and dark shades (e.g. L* = 98 / 5), but we'll fix this
by generating and overlaying modulated surface colors in our
ThemeOverlayController implementation.

Demo screenshots: https://twitter.com/kdrag0n/status/1445922541218922496

Change-Id: Icdc4957ecb4e0201377351f1a3e1c6928d6b3955

core/res/res/color/surface_header_dark_sysui.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:color="@color/system_neutral1_500" android:lStar="5" />
+</selector>

core/res/res/values-night/values.xml

@@ -22,6 +22,7 @@
         <item name="colorSecondary">@color/secondary_device_default_settings</item>
         <item name="colorAccent">@color/accent_device_default_dark</item>
         <item name="colorError">@color/error_color_device_default_dark</item>
+        <item name="colorSurfaceHeader">@color/surface_header_dark_sysui</item>
         <item name="colorControlNormal">?attr/textColorPrimary</item>
         <item name="alertDialogTheme">@style/Theme.DeviceDefault.Dialog.Alert</item>
         <item name="forceDarkAllowed">false</item>

packages/SystemUI/res/values/styles.xml

@@ -333,7 +333,7 @@
         <item name="android:windowIsFloating">true</item>
         <item name="android:homeAsUpIndicator">@drawable/ic_arrow_back</item>
         <item name="offStateColor">@*android:color/surface_light</item>
-        <item name="underSurfaceColor">@android:color/system_neutral1_50</item>
+        <item name="underSurfaceColor">@android:color/system_neutral1_100</item>
         <item name="android:colorBackground">@android:color/system_neutral1_50</item>
         <item name="android:itemTextAppearance">@style/Control.MenuItem</item>
     </style>

packages/SystemUI/src/com/android/systemui/statusbar/phone/ScrimController.java

@@ -180,6 +180,7 @@ public void setUnocclusionAnimationRunning(boolean unocclusionAnimationRunning)
     private UnlockedScreenOffAnimationController mUnlockedScreenOffAnimationController;
 
     private GradientColors mColors;
+    private GradientColors mBehindColors;
     private boolean mNeedsDrawableColorUpdate;
 
     private float mScrimBehindAlphaKeyguard = KEYGUARD_SCRIM_ALPHA;
@@ -276,6 +277,7 @@ public void onUiModeChanged() {
         );
 
         mColors = new GradientColors();
+        mBehindColors = new GradientColors();
     }
 
     /**
@@ -874,7 +876,7 @@ protected void updateScrims() {
                     && !mBlankScreen;
 
             mScrimInFront.setColors(mColors, animateScrimInFront);
-            mScrimBehind.setColors(mColors, animateBehindScrim);
+            mScrimBehind.setColors(mBehindColors, animateBehindScrim);
             mNotificationsScrim.setColors(mColors, animateScrimNotifications);
 
             dispatchBackScrimState(mScrimBehind.getViewAlpha());
@@ -1214,11 +1216,20 @@ private void updateThemeColors() {
         if (mScrimBehind == null) return;
         int background = Utils.getColorAttr(mScrimBehind.getContext(),
                 android.R.attr.colorBackgroundFloating).getDefaultColor();
+        int surfaceBackground = Utils.getColorAttr(mScrimBehind.getContext(),
+                com.android.internal.R.attr.colorSurfaceHeader).getDefaultColor();
         int accent = Utils.getColorAccent(mScrimBehind.getContext()).getDefaultColor();
+
         mColors.setMainColor(background);
         mColors.setSecondaryColor(accent);
         mColors.setSupportsDarkText(
                 ColorUtils.calculateContrast(mColors.getMainColor(), Color.WHITE) > 4.5);
+
+        mBehindColors.setMainColor(surfaceBackground);
+        mBehindColors.setSecondaryColor(accent);
+        mBehindColors.setSupportsDarkText(
+                ColorUtils.calculateContrast(mBehindColors.getMainColor(), Color.WHITE) > 4.5);
+
         mNeedsDrawableColorUpdate = true;
     }