Use getBoundingRects to add support inset MediaQuery/SafeArea when in freeform mode controls are shown. (#54294)

Original Title: Add FlutterViewDelegate and BoundingRect methods

Check the bounding rect for caption bar when sending viewport metrics to
Flutter to account for freeform mode. Use the more recent
`getBoundingRects` over `getInsets`.

Tests will need to be kept separate until Robolectric publishes a
version that supports API level 35.
Roboletric tests for this pr will be part of google testing until then. 
Pr for tests here https://critique.corp.google.com/cl/657302386. 

flutter/flutter#146658

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide] and the [C++,
Objective-C, Java style guides].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I added new tests to check the change I am making or feature I am
adding, or the PR is [test-exempt]. See [testing the engine] for
instructions on writing and running engine tests.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] I signed the [CLA].
- [x] All existing and new tests are passing.

Author: yaakovschectman

ci/licenses_golden/licenses_flutter

@@ -44060,6 +44060,7 @@ ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/Flu
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterSurfaceView.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterTextureView.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterView.java + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterViewDelegate.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyChannelResponder.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyData.java + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyEmbedderResponder.java + ../../../flutter/LICENSE
@@ -46946,6 +46947,7 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/Flutt
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterSurfaceView.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterTextureView.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterView.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/FlutterViewDelegate.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyChannelResponder.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyData.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/android/KeyEmbedderResponder.java

shell/platform/android/BUILD.gn

@@ -228,6 +228,7 @@ android_java_sources = [
   "io/flutter/embedding/android/FlutterSurfaceView.java",
   "io/flutter/embedding/android/FlutterTextureView.java",
   "io/flutter/embedding/android/FlutterView.java",
+  "io/flutter/embedding/android/FlutterViewDelegate.java",
   "io/flutter/embedding/android/KeyChannelResponder.java",
   "io/flutter/embedding/android/KeyData.java",
   "io/flutter/embedding/android/KeyEmbedderResponder.java",

shell/platform/android/io/flutter/embedding/android/FlutterView.java

@@ -772,6 +772,15 @@ navigationBarVisible && guessBottomKeyboardInset(insets) == 0
       viewportMetrics.viewInsetLeft = 0;
     }
 
+    // The caption bar inset is a new addition, and the APIs called to query it utilize a list of
+    // bounding Rects instead of an Insets object, which is a newer API method, as compared to the
+    // existing Insets-based method calls above.
+    if (Build.VERSION.SDK_INT >= API_LEVELS.API_35) {
+      delegate.growViewportMetricsToCaptionBar(getContext(), viewportMetrics);
+    } else {
+      Log.w(TAG, "API level " + Build.VERSION.SDK_INT + " is too low to query bounding rects.");
+    }
+
     Log.v(
         TAG,
         "Updating window insets (onApplyWindowInsets()):\n"
@@ -1449,6 +1458,13 @@ public void removeFlutterEngineAttachmentListener(
         .send();
   }
 
+  private FlutterViewDelegate delegate = new FlutterViewDelegate();
+
+  @VisibleForTesting
+  public void setDelegate(@NonNull FlutterViewDelegate delegate) {
+    this.delegate = delegate;
+  }
+
   private void sendViewportMetricsToFlutter() {
     if (!isAttachedToFlutterEngine()) {
       Log.w(
@@ -1460,6 +1476,7 @@ private void sendViewportMetricsToFlutter() {
 
     viewportMetrics.devicePixelRatio = getResources().getDisplayMetrics().density;
     viewportMetrics.physicalTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
+
     flutterEngine.getRenderer().setViewportMetrics(viewportMetrics);
   }
 
@@ -1485,6 +1502,15 @@ public void setVisibility(int visibility) {
     }
   }
 
+  /**
+   * Allow access to the viewport metrics so that tests can set them to be valid with nonzero
+   * dimensions.
+   */
+  @VisibleForTesting
+  public FlutterRenderer.ViewportMetrics getViewportMetrics() {
+    return viewportMetrics;
+  }
+
   /**
    * Listener that is notified when a {@link io.flutter.embedding.engine.FlutterEngine} is attached
    * to/detached from a given {@code FlutterView}.

shell/platform/android/io/flutter/embedding/android/FlutterViewDelegate.java

@@ -0,0 +1,71 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.embedding.android;
+
+import android.app.Activity;
+import android.content.Context;
+import android.graphics.Rect;
+import android.view.Window;
+import android.view.WindowInsets;
+import androidx.annotation.RequiresApi;
+import androidx.annotation.VisibleForTesting;
+import io.flutter.Build;
+import io.flutter.embedding.engine.renderer.FlutterRenderer;
+import io.flutter.util.ViewUtils;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * A delegate class that performs the task of retrieving the bounding rect values. Logic that is
+ * independent of the engine, or that tests must access in the absence of an engine, shall reside
+ * within this class.
+ */
+public class FlutterViewDelegate {
+  /**
+   * Return the WindowInsets object for the provided Context. A Context will only have a window if
+   * it is an instance of Activity. If context does not have a window, or it is not an activity,
+   * this method will return null. Otherwise, this method will return the WindowInsets for the
+   * provided activity's window.
+   */
+  @RequiresApi(api = Build.API_LEVELS.API_23)
+  @VisibleForTesting
+  public WindowInsets getWindowInsets(Context context) {
+    Activity activity = ViewUtils.getActivity(context);
+    if (activity == null) {
+      return null;
+    }
+    Window window = activity.getWindow();
+    if (window == null) {
+      return null;
+    }
+    return window.getDecorView().getRootWindowInsets();
+  }
+
+  @RequiresApi(api = Build.API_LEVELS.API_35)
+  public List<Rect> getCaptionBarInsets(Context context) {
+    WindowInsets insets = getWindowInsets(context);
+    if (insets == null) {
+      return Collections.emptyList();
+    }
+    return insets.getBoundingRects(WindowInsets.Type.captionBar());
+  }
+
+  @RequiresApi(api = Build.API_LEVELS.API_35)
+  public void growViewportMetricsToCaptionBar(
+      Context context, FlutterRenderer.ViewportMetrics viewportMetrics) {
+    List<Rect> boundingRects = getCaptionBarInsets(context);
+    int viewPaddingTop = viewportMetrics.viewPaddingTop;
+    for (Rect rect : boundingRects) {
+      viewPaddingTop = Math.max(viewPaddingTop, rect.bottom);
+    }
+    // The value getCaptionBarInset returns is only the bounding rects of the caption bar.
+    // When assigning the new value of viewPaddingTop, the maximum is taken with its old value
+    // to ensure that any previous top padding that is greater than that from the caption bar
+    // is not destroyed by this operation.
+    // Any potential update that will allow the caption bar to be positioned somewhere other than
+    // the top of the app window will require that this method be rewritten.
+    viewportMetrics.viewPaddingTop = viewPaddingTop;
+  }
+}

shell/platform/android/io/flutter/embedding/engine/renderer/FlutterRenderer.java

@@ -1271,6 +1271,9 @@ public static final class ViewportMetrics {
     public float devicePixelRatio = 1.0f;
     public int width = 0;
     public int height = 0;
+    // The fields prefixed with viewPadding and viewInset are used to calculate the padding,
+    // viewPadding, and viewInsets of ViewConfiguration in Dart. This calculation is performed at
+    // https://github.com/flutter/engine/blob/main/lib/ui/hooks.dart#L139-L155.
     public int viewPaddingTop = 0;
     public int viewPaddingRight = 0;
     public int viewPaddingBottom = 0;