diff --git a/core/java/android/app/Notification.java b/core/java/android/app/Notification.java
index 4b054f49d9104..8ac8e5e2224e5 100644
--- a/core/java/android/app/Notification.java
+++ b/core/java/android/app/Notification.java
@@ -5387,8 +5387,8 @@ public class Notification implements Parcelable
             contentView.setInt(R.id.expand_button, "setDefaultPillColor", pillColor);
             // Use different highlighted colors for conversations' unread count
             if (p.mHighlightExpander) {
-                pillColor = Colors.flattenAlpha(getPrimaryAccentColor(p), bgColor);
-                textColor = Colors.flattenAlpha(bgColor, pillColor);
+                pillColor = Colors.flattenAlpha(getColors(p).getTertiaryAccentColor(), bgColor);
+                textColor = Colors.flattenAlpha(getColors(p).getOnAccentTextColor(), pillColor);
             }
             contentView.setInt(R.id.expand_button, "setHighlightTextColor", textColor);
             contentView.setInt(R.id.expand_button, "setHighlightPillColor", pillColor);
@@ -12305,6 +12305,8 @@ public class Notification implements Parcelable
         private int mSecondaryTextColor = COLOR_INVALID;
         private int mPrimaryAccentColor = COLOR_INVALID;
         private int mSecondaryAccentColor = COLOR_INVALID;
+        private int mTertiaryAccentColor = COLOR_INVALID;
+        private int mOnAccentTextColor = COLOR_INVALID;
         private int mErrorColor = COLOR_INVALID;
         private int mContrastColor = COLOR_INVALID;
         private int mRippleAlpha = 0x33;
@@ -12362,7 +12364,7 @@ public class Notification implements Parcelable
 
             if (isColorized) {
                 if (rawColor == COLOR_DEFAULT) {
-                    int[] attrs = {R.attr.colorAccentTertiary};
+                    int[] attrs = {R.attr.colorAccentSecondary};
                     try (TypedArray ta = obtainDayNightAttributes(ctx, attrs)) {
                         mBackgroundColor = getColor(ta, 0, Color.WHITE);
                     }
@@ -12379,6 +12381,8 @@ public class Notification implements Parcelable
                 mContrastColor = mPrimaryTextColor;
                 mPrimaryAccentColor = mPrimaryTextColor;
                 mSecondaryAccentColor = mSecondaryTextColor;
+                mTertiaryAccentColor = flattenAlpha(mPrimaryTextColor, mBackgroundColor);
+                mOnAccentTextColor = mBackgroundColor;
                 mErrorColor = mPrimaryTextColor;
                 mRippleAlpha = 0x33;
             } else {
@@ -12389,6 +12393,8 @@ public class Notification implements Parcelable
                         R.attr.textColorSecondary,
                         R.attr.colorAccent,
                         R.attr.colorAccentSecondary,
+                        R.attr.colorAccentTertiary,
+                        R.attr.textColorOnAccent,
                         R.attr.colorError,
                         R.attr.colorControlHighlight
                 };
@@ -12399,8 +12405,10 @@ public class Notification implements Parcelable
                     mSecondaryTextColor = getColor(ta, 3, COLOR_INVALID);
                     mPrimaryAccentColor = getColor(ta, 4, COLOR_INVALID);
                     mSecondaryAccentColor = getColor(ta, 5, COLOR_INVALID);
-                    mErrorColor = getColor(ta, 6, COLOR_INVALID);
-                    mRippleAlpha = Color.alpha(getColor(ta, 7, 0x33ffffff));
+                    mTertiaryAccentColor = getColor(ta, 6, COLOR_INVALID);
+                    mOnAccentTextColor = getColor(ta, 7, COLOR_INVALID);
+                    mErrorColor = getColor(ta, 8, COLOR_INVALID);
+                    mRippleAlpha = Color.alpha(getColor(ta, 9, 0x33ffffff));
                 }
                 mContrastColor = calculateContrastColor(ctx, rawColor, mPrimaryAccentColor,
                         mBackgroundColor, nightMode);
@@ -12420,6 +12428,14 @@ public class Notification implements Parcelable
                 if (mSecondaryAccentColor == COLOR_INVALID) {
                     mSecondaryAccentColor = mContrastColor;
                 }
+                if (mTertiaryAccentColor == COLOR_INVALID) {
+                    mTertiaryAccentColor = mContrastColor;
+                }
+                if (mOnAccentTextColor == COLOR_INVALID) {
+                    mOnAccentTextColor = ColorUtils.setAlphaComponent(
+                            ContrastColorUtil.resolvePrimaryColor(
+                                    ctx, mTertiaryAccentColor, nightMode), 0xFF);
+                }
                 if (mErrorColor == COLOR_INVALID) {
                     mErrorColor = mPrimaryTextColor;
                 }
@@ -12485,6 +12501,16 @@ public class Notification implements Parcelable
             return mSecondaryAccentColor;
         }
 
+        /** @return the theme's tertiary accent color for colored UI elements. */
+        public @ColorInt int getTertiaryAccentColor() {
+            return mTertiaryAccentColor;
+        }
+
+        /** @return the theme's text color to be used on the tertiary accent color. */
+        public @ColorInt int getOnAccentTextColor() {
+            return mOnAccentTextColor;
+        }
+
         /**
          * @return the contrast-adjusted version of the color provided by the app, or the
          * primary text color when colorized.
diff --git a/core/tests/coretests/src/android/app/NotificationTest.java b/core/tests/coretests/src/android/app/NotificationTest.java
index cd07d464ee65d..685671b083c4a 100644
--- a/core/tests/coretests/src/android/app/NotificationTest.java
+++ b/core/tests/coretests/src/android/app/NotificationTest.java
@@ -399,6 +399,8 @@ public class NotificationTest {
             assertEquals(cDay.getSecondaryTextColor(), cNight.getSecondaryTextColor());
             assertEquals(cDay.getPrimaryAccentColor(), cNight.getPrimaryAccentColor());
             assertEquals(cDay.getSecondaryAccentColor(), cNight.getSecondaryAccentColor());
+            assertEquals(cDay.getTertiaryAccentColor(), cNight.getTertiaryAccentColor());
+            assertEquals(cDay.getOnAccentTextColor(), cNight.getOnAccentTextColor());
             assertEquals(cDay.getProtectionColor(), cNight.getProtectionColor());
             assertEquals(cDay.getContrastColor(), cNight.getContrastColor());
             assertEquals(cDay.getRippleAlpha(), cNight.getRippleAlpha());
@@ -413,20 +415,26 @@ public class NotificationTest {
         assertThat(c.getSecondaryTextColor()).isNotEqualTo(Notification.COLOR_INVALID);
         assertThat(c.getPrimaryAccentColor()).isNotEqualTo(Notification.COLOR_INVALID);
         assertThat(c.getSecondaryAccentColor()).isNotEqualTo(Notification.COLOR_INVALID);
+        assertThat(c.getTertiaryAccentColor()).isNotEqualTo(Notification.COLOR_INVALID);
+        assertThat(c.getOnAccentTextColor()).isNotEqualTo(Notification.COLOR_INVALID);
         assertThat(c.getErrorColor()).isNotEqualTo(Notification.COLOR_INVALID);
         assertThat(c.getContrastColor()).isNotEqualTo(Notification.COLOR_INVALID);
         assertThat(c.getRippleAlpha()).isAtLeast(0x00);
         assertThat(c.getRippleAlpha()).isAtMost(0xff);
 
-        // Assert that various colors have sufficient contrast
+        // Assert that various colors have sufficient contrast with the background
         assertContrastIsAtLeast(c.getPrimaryTextColor(), c.getBackgroundColor(), 4.5);
         assertContrastIsAtLeast(c.getSecondaryTextColor(), c.getBackgroundColor(), 4.5);
         assertContrastIsAtLeast(c.getPrimaryAccentColor(), c.getBackgroundColor(), 4.5);
         assertContrastIsAtLeast(c.getErrorColor(), c.getBackgroundColor(), 4.5);
         assertContrastIsAtLeast(c.getContrastColor(), c.getBackgroundColor(), 4.5);
 
-        // This accent color is only used for emphasized buttons
+        // These colors are only used for emphasized buttons; they do not need contrast
         assertContrastIsAtLeast(c.getSecondaryAccentColor(), c.getBackgroundColor(), 1);
+        assertContrastIsAtLeast(c.getTertiaryAccentColor(), c.getBackgroundColor(), 1);
+
+        // The text that is used within the accent color DOES need to have contrast
+        assertContrastIsAtLeast(c.getOnAccentTextColor(), c.getTertiaryAccentColor(), 4.5);
     }
 
     private void assertContrastIsAtLeast(int foreground, int background, double minContrast) {