Subframes in inner WebContents should not create proxies in process of outer WebContents.

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

 // Copyright (c) 2012 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.
 
 var util = {};
 var embedder = {};
 embedder.baseGuestURL = '';
 embedder.emptyGuestURL = '';
 embedder.windowOpenGuestURL = '';
 embedder.noReferrerGuestURL = '';
@@ skipping 1314 matching lines @@
     if (loadCommitCount > 3) {
       embedder.test.fail();
     }
   });
   document.body.appendChild(webview);
   webview.src = testPage1;
   webview.src = testPage2;
   webview.src = testPage3;
 }
 
+function testNestedSubframes() {
+  var webview = document.createElement('webview');
+  webview.partition = 'foobar';
+  var nestedFrameURL = 'parent_frame.html';
+  webview.onconsolemessage = function(e) {
+    window.console.log('G: ' + e.message);

[lfg, 2015/07/31 19:35:29]

Is this needed? If yes, then G wasn't very obvious when I saw it, I assume it's
Guest? Can you make it more explicit?

[lazyboy, 2015/07/31 20:36:47]

Not a requirement, this is just log, I've made it explicit.
Done.

+  };
+  webview.onloadstop = function() {
+    window.onmessage = function(e) {
+      if (e.data == 'frames-loaded') {
+        embedder.test.succeed();
+      }
+    };
+
+    // Ask the <webview> to load nested frames. It will reply via postMessage
+    // once frames have finished loading.
+    webview.contentWindow.postMessage('load-frames', '*');
+  };
+  webview.onloadabort = embedder.test.fail;
+
+  webview.src = nestedFrameURL;
+  document.body.appendChild(webview);
+};
+
 // This test verifies that we can set the <webview> src multiple times and the
 // changes will cause a navigation.
 function testNavOnSrcAttributeChange() {
   var testPage1 = 'data:text/html,test page 1';
   var testPage2 = 'data:text/html,test page 2';
   var testPage3 = 'data:text/html,test page 3';
   var tests = [testPage1, testPage2, testPage3];
   var webview = new WebView();
   webview.partition = arguments.callee.name;
   var loadCommitCount = 0;
@@ skipping 1454 matching lines @@
   'testAddContentScriptWithCode': testAddContentScriptWithCode,
   'testExecuteScriptFail': testExecuteScriptFail,
   'testExecuteScript': testExecuteScript,
   'testExecuteScriptIsAbortedWhenWebViewSourceIsChanged':
       testExecuteScriptIsAbortedWhenWebViewSourceIsChanged,
   'testTerminateAfterExit': testTerminateAfterExit,
   'testAssignSrcAfterCrash': testAssignSrcAfterCrash,
   'testNavOnConsecutiveSrcAttributeChanges':
       testNavOnConsecutiveSrcAttributeChanges,
   'testNavOnSrcAttributeChange': testNavOnSrcAttributeChange,
+  'testNestedSubframes': testNestedSubframes,
   'testReassignSrcAttribute': testReassignSrcAttribute,
   'testRemoveSrcAttribute': testRemoveSrcAttribute,
   'testPluginLoadInternalResource': testPluginLoadInternalResource,
   'testPluginLoadPermission': testPluginLoadPermission,
   'testNewWindow': testNewWindow,
   'testNewWindowTwoListeners': testNewWindowTwoListeners,
   'testNewWindowNoPreventDefault': testNewWindowNoPreventDefault,
   'testNewWindowNoReferrerLink': testNewWindowNoReferrerLink,
   'testContentLoadEvent': testContentLoadEvent,
   'testContentLoadEventWithDisplayNone': testContentLoadEventWithDisplayNone,
@@ skipping 44 matching lines @@
   'testPDFInWebview': testPDFInWebview,
   'testMailtoLink': testMailtoLink
 };
 
 onload = function() {
   chrome.test.getConfig(function(config) {
     embedder.setUp_(config);
     chrome.test.sendMessage("Launched");
   });
 };