Implement declarative content script API for <webview> [js part].

chrome/test/data/extensions/platform_apps/web_view/shim/main.js

Index: chrome/test/data/extensions/platform_apps/web_view/shim/main.js
diff --git a/chrome/test/data/extensions/platform_apps/web_view/shim/main.js b/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
index 4778664caca6ef91b607e19702baebf3d8fd0f18..b9d4bf6e59e7ed1c798c13d846adba2860f53085 100644
--- a/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
+++ b/chrome/test/data/extensions/platform_apps/web_view/shim/main.js
@@ -545,6 +545,38 @@ function testWebRequestAPIExistence() {
   document.body.appendChild(webview);
 }
 
+function testDeclarativeContentAPIExistence() {
+  var apiPropertiesToCheck = [
+    // Declarative Content API.
+    'onPageChanged'
+  ];
+  var webview = document.createElement('webview');
+  webview.setAttribute('partition', arguments.callee.name);
+  webview.addEventListener('loadstop', function(e) {
+    for (var i = 0; i < apiPropertiesToCheck.length; ++i) {
+      embedder.test.assertEq('object',
+                             typeof webview.request[apiPropertiesToCheck[i]]);
+      embedder.test.assertEq(
+          'function',
+          typeof webview.request[apiPropertiesToCheck[i]].addRules);
+      embedder.test.assertEq(
+          'function',
+          typeof webview.request[apiPropertiesToCheck[i]].getRules);
+      embedder.test.assertEq(
+          'function',
+          typeof webview.request[apiPropertiesToCheck[i]].removeRules);
+    }
+
+    // Try to overwrite webview.request, shall not succeed.
+    webview.request = '123';
+    embedder.test.assertTrue(typeof webview.request !== 'string');
+
+    embedder.test.succeed();
+  });
+  webview.setAttribute('src', 'data:text/html,webview check api');
+  document.body.appendChild(webview);
+}
+
 // This test verifies that the loadstart, loadstop, and exit events fire as
 // expected.
 function testEventName() {
@@ -2016,6 +2048,7 @@ embedder.test.testList = {
       testInlineScriptFromAccessibleResources,
   'testInvalidChromeExtensionURL': testInvalidChromeExtensionURL,
   'testWebRequestAPIExistence': testWebRequestAPIExistence,
+  'testDeclarativeContentAPIExistence': testDeclarativeContentAPIExistence,
   'testEventName': testEventName,
   'testOnEventProperties': testOnEventProperties,
   'testLoadProgressEvent': testLoadProgressEvent,