[Extension ServiceWorkers] Adding getBackgroundClient

After the v8::Context for a service worker is passed up, a script is injected in order for the service worker to have access to the background page of the extension.

BUG=501569

Review URL: https://codereview.chromium.org/1304663003

Cr-Commit-Position: refs/heads/master@{#344900}

2 files changed, 27 insertions, 0 deletions

diff --git a/extensions/renderer/resources/extensions_renderer_resources.grd b/extensions/renderer/resources/extensions_renderer_resources.grd
index 5d20a15..d3fcb7d 100644
--- a/extensions/renderer/resources/extensions_renderer_resources.grd
+++ b/extensions/renderer/resources/extensions_renderer_resources.grd
@@ -80,6 +80,7 @@
       <include name="IDR_PERMISSIONS_CUSTOM_BINDINGS_JS" file="permissions_custom_bindings.js" type="BINDATA" />
       <include name="IDR_PRINTER_PROVIDER_CUSTOM_BINDINGS_JS" file="printer_provider_custom_bindings.js" type="BINDATA" />
       <include name="IDR_RUNTIME_CUSTOM_BINDINGS_JS" file="runtime_custom_bindings.js" type="BINDATA" />
+      <include name="IDR_SERVICE_WORKER_BINDINGS_JS" file="service_worker_bindings.js" type="BINDATA" />
       <include name="IDR_WEB_REQUEST_CUSTOM_BINDINGS_JS" file="web_request_custom_bindings.js" type="BINDATA" />
       <include name="IDR_WEB_REQUEST_INTERNAL_CUSTOM_BINDINGS_JS" file="web_request_internal_custom_bindings.js" type="BINDATA" />
       <include name="IDR_WINDOW_CONTROLS_JS" file="window_controls.js" type="BINDATA" />
diff --git a/extensions/renderer/resources/service_worker_bindings.js b/extensions/renderer/resources/service_worker_bindings.js
new file mode 100644
index 0000000..bc8cfd6b
--- /dev/null
+++ b/extensions/renderer/resources/service_worker_bindings.js
@@ -0,0 +1,26 @@
+// Copyright 2015 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.
+
+(function(backgroundUrl) {
+  'use strict';
+
+  self.chrome = self.chrome || {};
+
+  self.chrome.getBackgroundClient = function() { return new Promise(
+   function(resolve, reject) {
+     self.clients.matchAll({
+      includeUncontrolled: true,
+      type: 'window'
+     }).then(function(clients) {
+      for (let client of clients) {
+         if (client.url == backgroundUrl) {
+           resolve(client);
+           return;
+         }
+       }
+       reject("BackgroundClient ('" + backgroundUrl + "') does not exist.")
+     })
+    });
+  }
+});