Track where WebContents are created in order to better understand issue.

ui/app_list/demo/app_list_demo_views.cc

 // Copyright 2014 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.
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/run_loop.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/browser/web_contents_source.h"
 #include "content/public/common/content_switches.h"
 #include "ui/app_list/test/app_list_test_model.h"
 #include "ui/app_list/test/app_list_test_view_delegate.h"
 #include "ui/app_list/views/app_list_view.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/resources/grit/ui_resources.h"
 #include "ui/views/controls/webview/webview.h"
 #include "ui/views_content_client/views_content_client.h"
 
 #if defined(OS_WIN)
@@ skipping 68 matching lines @@
 void DemoAppListViewDelegate::ViewClosing() {
   base::MessageLoop* message_loop = base::MessageLoopForUI::current();
   message_loop->DeleteSoon(FROM_HERE, this);
   message_loop->QuitWhenIdle();
 }
 
 views::View* DemoAppListViewDelegate::CreateStartPageWebView(
     const gfx::Size& size) {
   web_contents_.reset(content::WebContents::Create(
       content::WebContents::CreateParams(browser_context_)));
+  WebContentsSource::CreateForWebContentsAndLocation(web_contents_.get(),
+                                                     FROM_HERE);
   web_contents_->GetController().LoadURL(GURL("http://www.google.com/"),
                                          content::Referrer(),
                                          ui::PAGE_TRANSITION_AUTO_TOPLEVEL,
                                          std::string());
   views::WebView* web_view = new views::WebView(
       web_contents_->GetBrowserContext());
   web_view->SetPreferredSize(size);
   web_view->SetWebContents(web_contents_.get());
   return web_view;
 }
@@ skipping 15 matching lines @@
   content::InitializeSandboxInfo(&sandbox_info);
   ui::ViewsContentClient views_content_client(instance, &sandbox_info);
 #else
 int main(int argc, const char** argv) {
   ui::ViewsContentClient views_content_client(argc, argv);
 #endif
 
   views_content_client.set_task(base::Bind(&ShowAppList));
   return views_content_client.RunMain();
 }