Add browser_proxy.js as the bridge to implement echeapi.d.ts

Bug: b/178379656
Change-Id: I819b18bca7df55691fdd57ecaee94f5ebaf69617
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2717248
Reviewed-by: Daniel Nishi <dhnishi@chromium.org>
Commit-Queue: Guanru Lee <guanrulee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#858426}

chromeos/components/eche_app_ui/BUILD.gn

@@ -39,7 +39,10 @@ js_type_check("closure_compile") {
 }
 
 js_library("app") {
-  sources = [ "resources/prod/js/app_bundle.js" ]
+  sources = [
+    "resources/browser_proxy.js",
+    "resources/prod/js/app_bundle.js",
+  ]
 }
 
 js2gtest("browser_tests_js") {
@@ -50,11 +53,9 @@ js2gtest("browser_tests_js") {
   defines = [ "HAS_OUT_OF_PROC_TEST_RUNNER" ]
 }
 
-# TODO(b/176936453): add js files for mojo API and remove
-# the dummy icon once adding in the real resources.
 generate_grd("build_grd") {
   input_files_base_dir = rebase_path("resources", "//")
-  input_files = [ "eche_icon_256.png" ]
+  input_files = [ "browser_proxy.js" ]
   manifest_files = []
   grd_prefix = "chromeos_eche_app"
   out_grd = "$target_gen_dir/${grd_prefix}_resources.grd"

chromeos/components/eche_app_ui/eche_app_ui.cc

@@ -7,6 +7,7 @@
 #include <memory>
 
 #include "chromeos/components/eche_app_ui/url_constants.h"
+#include "chromeos/grit/chromeos_eche_app_resources.h"
 #include "chromeos/grit/chromeos_eche_bundle_resources.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_ui.h"
@@ -28,6 +29,8 @@ EcheAppUI::EcheAppUI(content::WebUI* web_ui) : ui::MojoWebUIController(web_ui) {
                                IDR_CHROMEOS_ECHE_APP_BUNDLE_JS);
   html_source->AddResourcePath("assets/app_bundle.css",
                                IDR_CHROMEOS_ECHE_APP_BUNDLE_CSS);
+  html_source->AddResourcePath("browser_proxy.js",
+                               IDR_CHROMEOS_ECHE_APP_BROWSER_PROXY_JS);
 
   // DisableTrustedTypesCSP to support TrustedTypePolicy named 'goog#html'.
   // It is the Closure templating system that renders our UI, as it does many

chromeos/components/eche_app_ui/resources/browser_proxy.js

@@ -0,0 +1,23 @@
+// Copyright 2021 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.
+
+// The implementation of echeapi.d.ts
+const EcheApiBindingImpl = new class {
+  onWebRtcSignalReceived(callback) {
+    // TODO(b/178379656): hook the callback to mojo interface.
+  }
+
+  sendWebRtcSignal(signaling) {
+    // TODO(b/178379656): hook the sending function to mojo interface.
+  }
+};
+
+// Declare module echeapi and bind the implementation to echeapi.d.ts
+const echeapi = {};
+echeapi.webrtc = {};
+echeapi.webrtc.sendSignal =
+EcheApiBindingImpl.sendWebRtcSignal.bind(EcheApiBindingImpl);
+echeapi.webrtc.registerSignalReceiver =
+EcheApiBindingImpl.onWebRtcSignalReceived.bind(EcheApiBindingImpl);
+window['echeapi'] = echeapi;