Enable CSS grid layout in test_shell to ease development.

webkit/tools/test_shell/webview_host_mac.mm

 // 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "webkit/tools/test_shell/webview_host.h"
 #include "webkit/tools/test_shell/mac/test_shell_webview.h"
 
 #include "skia/ext/platform_canvas.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebSize.h"
+#include "third_party/WebKit/Source/WebKit/chromium/public/WebSettings.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/WebView.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 #include "webkit/glue/webpreferences.h"
 #include "webkit/tools/test_shell/test_shell.h"
 #include "webkit/tools/test_shell/test_webview_delegate.h"
 
 using WebKit::WebDevToolsAgentClient;
 using WebKit::WebSize;
 using WebKit::WebView;
@@ skipping 13 matching lines @@
   content_rect.size.height -= 32;
   host->view_ = [[TestShellWebView alloc] initWithFrame:content_rect];
   // make the height and width track the window size.
   [host->view_ setAutoresizingMask:(NSViewWidthSizable | NSViewHeightSizable)];
   [parent_view addSubview:host->view_];
   [host->view_ release];
 
   host->webwidget_ = WebView::create(delegate);
   host->webview()->setDevToolsAgentClient(dev_tools_client);
   prefs.Apply(host->webview());
+  host->webview()->settings()->setExperimentalCSSGridLayoutEnabled(true);
   host->webview()->initializeMainFrame(delegate);
   host->webwidget_->resize(WebSize(NSWidth(content_rect),
                                    NSHeight(content_rect)));
 
   return host;
 }
 
 WebView* WebViewHost::webview() const {
   return static_cast<WebView*>(webwidget_);
 }
 
 void WebViewHost::SetIsActive(bool active) {
   // Ignore calls in layout test mode so that tests don't mess with each other
   // when running in parallel.
   if (!TestShell::layout_test_mode())
     webview()->setIsActive(active);
 }