Update connected display config on settings load.

Bug: 128354502
Test: Manual test.
atest DisplayWindowSettingsTests
atest RootWindowContainerTests
Change-Id: I2b85735d4b27516f5cb69d34592ae856208df25e

services/core/java/com/android/server/wm/ActivityTaskManagerService.java

@@ -748,6 +748,7 @@ public class ActivityTaskManagerService extends IActivityTaskManager.Stub {
             mWindowManager.setSupportsPictureInPicture(mSupportsPictureInPicture);
             mWindowManager.setSupportsFreeformWindowManagement(mSupportsFreeformWindowManagement);
             mWindowManager.setIsPc(isPc);
+            mWindowManager.mRoot.onSettingsRetrieved();
             // This happens before any activities are started, so we can change global configuration
             // in-place.
             updateConfigurationLocked(configuration, null, true);

services/core/java/com/android/server/wm/DisplayWindowSettings.java

@@ -352,6 +352,24 @@ class DisplayWindowSettings {
         dc.mDisplayScalingDisabled = entry.mForcedScalingMode == FORCE_SCALING_MODE_DISABLED;
     }
 
+    /**
+     * Updates settings for the given display after system features are loaded into window manager
+     * service, e.g. if this device is PC and if this device supports freeform.
+     *
+     * @param dc the given display.
+     * @return {@code true} if any settings for this display has changed; {@code false} if nothing
+     * changed.
+     */
+    boolean updateSettingsForDisplay(DisplayContent dc) {
+        if (dc.getWindowingMode() != getWindowingModeLocked(dc)) {
+            // For the time being the only thing that may change is windowing mode, so just update
+            // that.
+            dc.setWindowingMode(getWindowingModeLocked(dc));
+            return true;
+        }
+        return false;
+    }
+
     private void readSettings() {
         FileInputStream stream;
         try {

services/core/java/com/android/server/wm/RootWindowContainer.java

@@ -245,6 +245,34 @@ class RootWindowContainer extends WindowContainer<DisplayContent>
         return dc;
     }
 
+    /**
+     * Called when DisplayWindowSettings values may change.
+     */
+    void onSettingsRetrieved() {
+        final int numDisplays = mChildren.size();
+        for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {
+            final DisplayContent displayContent = mChildren.get(displayNdx);
+            final boolean changed = mWmService.mDisplayWindowSettings.updateSettingsForDisplay(
+                    displayContent);
+            if (!changed) {
+                continue;
+            }
+
+            displayContent.initializeDisplayOverrideConfiguration();
+            mWmService.reconfigureDisplayLocked(displayContent);
+
+            // We need to update global configuration as well if config of default display has
+            // changed. Do it inline because ATMS#retrieveSettings() will soon update the
+            // configuration inline, which will overwrite the new windowing mode.
+            if (displayContent.isDefaultDisplay) {
+                final Configuration newConfig = mWmService.computeNewConfiguration(
+                        displayContent.getDisplayId());
+                mWmService.mAtmService.updateConfigurationLocked(newConfig, null /* starting */,
+                        false /* initLocale */);
+            }
+        }
+    }
+
     boolean isLayoutNeeded() {
         final int numDisplays = mChildren.size();
         for (int displayNdx = 0; displayNdx < numDisplays; ++displayNdx) {

services/tests/wmtests/src/com/android/server/wm/DisplayWindowSettingsTests.java

@@ -147,6 +147,19 @@ public class DisplayWindowSettingsTests extends WindowTestsBase {
                 mPrimaryDisplay.getWindowingMode());
     }
 
+    @Test
+    public void testPrimaryDisplayUpdateToFreeform_HasFreeformSupport_IsPc() {
+        mTarget.applySettingsToDisplayLocked(mPrimaryDisplay);
+
+        mWm.setSupportsFreeformWindowManagement(true);
+        mWm.setIsPc(true);
+
+        mTarget.updateSettingsForDisplay(mPrimaryDisplay);
+
+        assertEquals(WindowConfiguration.WINDOWING_MODE_FREEFORM,
+                mPrimaryDisplay.getWindowingMode());
+    }
+
     @Test
     public void testSecondaryDisplayDefaultToFullscreen_NoFreeformSupport() {
         mTarget.applySettingsToDisplayLocked(mSecondaryDisplay);

services/tests/wmtests/src/com/android/server/wm/RootWindowContainerTests.java

@@ -20,9 +20,11 @@ import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_STATUS_BAR;
 import static android.view.WindowManager.LayoutParams.TYPE_TOAST;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
+import android.app.WindowConfiguration;
 import android.platform.test.annotations.Presubmit;
 
 import androidx.test.filters.SmallTest;
@@ -71,5 +73,21 @@ public class RootWindowContainerTests extends WindowTestsBase {
         assertFalse(app.isVisible());
         assertFalse(mWm.mRoot.isAnyNonToastWindowVisibleForUid(FAKE_CALLING_UID));
     }
+
+    @Test
+    public void testUpdateDefaultDisplayWindowingModeOnSettingsRetrieved() {
+        synchronized (mWm.mGlobalLock) {
+            assertEquals(WindowConfiguration.WINDOWING_MODE_FULLSCREEN,
+                    mWm.getDefaultDisplayContentLocked().getWindowingMode());
+
+            mWm.mIsPc = true;
+            mWm.mSupportsFreeformWindowManagement = true;
+
+            mWm.mRoot.onSettingsRetrieved();
+
+            assertEquals(WindowConfiguration.WINDOWING_MODE_FREEFORM,
+                    mWm.getDefaultDisplayContentLocked().getWindowingMode());
+        }
+    }
 }