Move initialization from onCreate to attachBaseContext

Previously we initialize WindowManager and associate DisplayArea in onCreate,
but apps may use WindowManager before WindowProviderService#onCreate.
The code may be like:
```
public void onCreate() {
    WindowManager wm = getSystemService(Windowmanager.class);
    wm.getCurrentWindowMetrics().getBounds(); // <--- crash here
    super.onCreate()
    ...
}
```
This CL move the initialization step to attachBaseContext to prevent
the crash.

Test: atest WindowContextTests
Test: run gsi_avd/boot_health/vendor_img_rvc on ABTD
Bug: 191635763
Change-Id: Id8bad73a749813a90b307ac2b4d020f740631ea3

core/java/android/window/WindowProviderService.java

@@ -53,6 +53,7 @@ public abstract class WindowProviderService extends Service {
     private final WindowTokenClient mWindowToken = new WindowTokenClient();
     private final WindowContextController mController = new WindowContextController(mWindowToken);
     private WindowManager mWindowManager;
+    private boolean mInitialized;
 
     /**
      * Returns the type of this {@link WindowProviderService}.
@@ -122,13 +123,17 @@ public abstract class WindowProviderService extends Service {
         return context.createTokenContext(mWindowToken, display);
     }
 
-    @CallSuper
+    /** @hide */
     @Override
-    public void onCreate() {
-        super.onCreate();
-        mWindowToken.attachContext(this);
-        mController.attachToDisplayArea(getWindowType(), getDisplayId(), getWindowContextOptions());
-        mWindowManager = WindowManagerImpl.createWindowContextWindowManager(this);
+    protected void attachBaseContext(Context newBase) {
+        super.attachBaseContext(newBase);
+        if (!mInitialized) {
+            mWindowToken.attachContext(this);
+            mController.attachToDisplayArea(getWindowType(), getDisplayId(),
+                    getWindowContextOptions());
+            mWindowManager = WindowManagerImpl.createWindowContextWindowManager(this);
+            mInitialized = true;
+        }
     }
 
     @SuppressLint("OnNameExpected")