Migrate ENABLE_GRID_ONLY_OVERVIEW to aconfig

- Keeping FeatureFlags.ENABLE_GRID_ONLY_OVERVIEW for local testing until aconfig is available in FlagFlipper
- Still reference ENABLE_GRID_ONLY_OVERVIEW in tests as aconfig still can't be mocked

Bug: 270397206
Test: manual
Change-Id: I799e05311adc21184a6ad7ce92a3abdab3f25c25
diff --git a/src/com/android/launcher3/config/FeatureFlags.java b/src/com/android/launcher3/config/FeatureFlags.java
index 03a7d87..574f87b 100644
--- a/src/com/android/launcher3/config/FeatureFlags.java
+++ b/src/com/android/launcher3/config/FeatureFlags.java
@@ -27,6 +27,7 @@
 import androidx.annotation.VisibleForTesting;
 
 import com.android.launcher3.BuildConfig;
+import com.android.launcher3.Flags;
 import com.android.launcher3.Utilities;
 
 import java.util.function.Predicate;
@@ -312,9 +313,14 @@
                     + "start receiving the events");
 
     // TODO(Block 23): Clean up flags
+    // Aconfig migration complete for ENABLE_GRID_ONLY_OVERVIEW.
+    @VisibleForTesting
     public static final BooleanFlag ENABLE_GRID_ONLY_OVERVIEW = getDebugFlag(270397206,
             "ENABLE_GRID_ONLY_OVERVIEW", TEAMFOOD,
             "Enable a grid-only overview without a focused task.");
+    public static boolean enableGridOnlyOverview() {
+        return ENABLE_GRID_ONLY_OVERVIEW.get() || Flags.enableGridOnlyOverview();
+    }
 
     public static final BooleanFlag ENABLE_CURSOR_HOVER_STATES = getDebugFlag(243191650,
             "ENABLE_CURSOR_HOVER_STATES", TEAMFOOD,