Add a unit test for the experimental app list.

ui/app_list/views/start_page_view.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 "ui/app_list/views/start_page_view.h"
 
 #include "content/public/browser/web_contents.h"
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/views/app_list_main_view.h"
 #include "ui/gfx/canvas.h"
@@ skipping 54 matching lines @@
 
 StartPageView::StartPageView(AppListMainView* app_list_main_view,
                              content::WebContents* start_page_web_contents)
     : app_list_main_view_(app_list_main_view),
       instant_container_(new views::View) {
   AddChildView(instant_container_);
   SetLayoutManager(new views::BoxLayout(views::BoxLayout::kVertical, 0, 0, 0));
   instant_container_->SetLayoutManager(new views::BoxLayout(
       views::BoxLayout::kVertical, 0, kTopMargin, kInstantContainerSpacing));
 
-  views::WebView* web_view =
-      new views::WebView(start_page_web_contents->GetBrowserContext());
+  views::WebView* web_view = new views::WebView(
+      start_page_web_contents ? start_page_web_contents->GetBrowserContext()
+                              : NULL);
   web_view->SetPreferredSize(gfx::Size(kWebViewWidth, kWebViewHeight));
   web_view->SetWebContents(start_page_web_contents);
 
   instant_container_->AddChildView(web_view);
   instant_container_->AddChildView(new BarPlaceholderButton(this));
 }
 
 StartPageView::~StartPageView() {
 }
 
 void StartPageView::Reset() {
   instant_container_->SetVisible(true);
 }
 
 void StartPageView::ButtonPressed(views::Button* sender,
                                   const ui::Event& event) {
   app_list_main_view_->OnStartPageSearchButtonPressed();
   instant_container_->SetVisible(false);
 }
 
 }  // namespace app_list