Add a command-line switch --enable-per-tile-painting.

chrome/browser/tab_contents/render_view_host_delegate_helper.cc

 // Copyright (c) 2011 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 "chrome/browser/tab_contents/render_view_host_delegate_helper.h"
 
 #include "base/command_line.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/background/background_contents_service.h"
@@ skipping 487 matching lines @@
     if (profile->GetUserStyleSheetWatcher()) {
       web_prefs.user_style_sheet_enabled = true;
       web_prefs.user_style_sheet_location =
           profile->GetUserStyleSheetWatcher()->user_style_sheet();
     } else {
       web_prefs.user_style_sheet_enabled = false;
     }
 
     web_prefs.visual_word_movement_enabled =
         command_line.HasSwitch(switches::kEnableVisualWordMovement);
+    web_prefs.per_tile_drawing_enabled =
+        command_line.HasSwitch(switches::kEnablePerTileDrawing);
   }
 
   {  // Certain GPU features might have been blacklisted.
     GpuDataManager* gpu_data_manager = GpuDataManager::GetInstance();
     DCHECK(gpu_data_manager);
     uint32 blacklist_flags = gpu_data_manager->GetGpuFeatureFlags().flags();
     if (blacklist_flags & GpuFeatureFlags::kGpuFeatureAcceleratedCompositing)
       web_prefs.accelerated_compositing_enabled = false;
     if (blacklist_flags & GpuFeatureFlags::kGpuFeatureWebgl)
       web_prefs.experimental_webgl_enabled = false;
@@ skipping 63 matching lines @@
   DictionaryValue* inspector_settings = update.Get();
   inspector_settings->SetWithoutPathExpansion(key,
                                               Value::CreateStringValue(value));
 }
 
 void RenderViewHostDelegateHelper::ClearInspectorSettings(
     content::BrowserContext* browser_context) {
   Profile::FromBrowserContext(browser_context)->GetPrefs()->
       ClearPref(prefs::kWebKitInspectorSettings);
 }