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

ui/keyboard/content/keyboard_ui_content.cc

 // Copyright (c) 2013 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 "ui/keyboard/content/keyboard_ui_content.h"
 
 #include "base/command_line.h"
 #include "base/values.h"
 #include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_iterator.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
-#include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_source.h"
 #include "content/public/browser/web_ui.h"
 #include "content/public/common/bindings_policy.h"
 #include "ui/aura/layout_manager.h"
 #include "ui/aura/window.h"
 #include "ui/base/ime/input_method.h"
 #include "ui/base/ime/text_input_client.h"
 #include "ui/keyboard/content/keyboard_constants.h"
 #include "ui/keyboard/keyboard_controller.h"
 #include "ui/keyboard/keyboard_switches.h"
 #include "ui/keyboard/keyboard_util.h"
@@ skipping 155 matching lines @@
   }
 }
 
 aura::Window* KeyboardUIContent::GetKeyboardWindow() {
   if (!keyboard_contents_) {
     content::BrowserContext* context = browser_context();
     keyboard_contents_.reset(content::WebContents::Create(
         content::WebContents::CreateParams(context,
             content::SiteInstance::CreateForURL(context,
                                                 GetVirtualKeyboardUrl()))));
+    WebContentsSource::CreateForWebContentsAndLocation(keyboard_contents_.get(),
+                                                       FROM_HERE);
     keyboard_contents_->SetDelegate(new KeyboardContentsDelegate(this));
     SetupWebContents(keyboard_contents_.get());
     LoadContents(GetVirtualKeyboardUrl());
     keyboard_contents_->GetNativeView()->AddObserver(this);
   }
 
   return keyboard_contents_->GetNativeView();
 }
 
 bool KeyboardUIContent::HasKeyboardWindow() const {
@@ skipping 119 matching lines @@
           keyboard_controller()->keyboard_visible());
 }
 
 void KeyboardUIContent::AddBoundsChangedObserver(aura::Window* window) {
   aura::Window* target_window = window ? window->GetToplevelWindow() : nullptr;
   if (target_window)
     window_bounds_observer_->AddObservedWindow(target_window);
 }
 
 }  // namespace keyboard