Replace String with WebMessagePayload for AndroidX WebMessage API

Design doc: https://docs.google.com/document/d/1nsQnwwY43OuA4PsSaMioiKA0c_M1eV1XX2q15YFA7cI/edit?usp=sharing

This CL did not add new features.
- Add a new boundary type WebMessagePayload to replace String
WebMessage.getData().
- Add new data class MessagePayload in content/, and replace existing
PostMessage API with the new type.
- A followup change will add ArrayBuffer support in
WebViewCompat.postMessageToMainFrame and
WebChannelCompat.postMessage.

How to test: run tests in existing AndroidX Webkit.

Bug: 1023334
Change-Id: Ib5b35b974bee597a6efada75503c5288f7058c50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3583520
Reviewed-by: Bo Liu <boliu@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Peter Conn <peconn@chromium.org>
Commit-Queue: Linyue He <linyhe@microsoft.com>
Cr-Commit-Position: refs/heads/main@{#995852}
NOKEYCHECK=True
GitOrigin-RevId: bc7514a7cf7b67ffc3fb0698310a23246df5a7c5

1 files changed, 28 insertions, 0 deletions

diff --git a/src/org/chromium/support_lib_boundary/WebMessagePayloadBoundaryInterface.java b/src/org/chromium/support_lib_boundary/WebMessagePayloadBoundaryInterface.java
new file mode 100644
index 0000000..1a4d6b5
--- /dev/null
+++ b/src/org/chromium/support_lib_boundary/WebMessagePayloadBoundaryInterface.java
@@ -0,0 +1,28 @@
+// Copyright 2022 The Chromium 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 org.chromium.support_lib_boundary;
+
+import androidx.annotation.IntDef;
+import androidx.annotation.Nullable;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Boundary interface for WebMessagePayload.
+ */
+public interface WebMessagePayloadBoundaryInterface extends FeatureFlagHolderBoundaryInterface {
+    @WebMessagePayloadType
+    int getType();
+
+    @Nullable
+    String getAsString();
+
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef(flag = true, value = {WebMessagePayloadType.TYPE_STRING})
+    @interface WebMessagePayloadType {
+        int TYPE_STRING = 0;
+    }
+}