Chromium side plumbing for enabling fixed root background compositing.

content/renderer/render_view_impl.cc

 // 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.
 
 #include "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 587 matching lines @@
 
   if (command_line.HasSwitch(switches::kDisableCompositingForTransition))
     return false;
 
   if (command_line.HasSwitch(switches::kEnableCompositingForTransition))
     return true;
 
   return DeviceScaleEnsuresTextQuality(device_scale_factor);
 }
 
+static bool ShouldUseAcceleratedFixedRootBackground(float device_scale_factor) {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableAcceleratedFixedRootBackground))
+    return false;
+
+  if (command_line.HasSwitch(switches::kEnableAcceleratedFixedRootBackground))
+    return true;
+
+  return DeviceScaleEnsuresTextQuality(device_scale_factor);
+}
+
 static FaviconURL::IconType ToFaviconType(WebKit::WebIconURL::Type type) {
   switch (type) {
     case WebKit::WebIconURL::TypeFavicon:
       return FaviconURL::FAVICON;
     case WebKit::WebIconURL::TypeTouch:
       return FaviconURL::TOUCH_ICON;
     case WebKit::WebIconURL::TypeTouchPrecomposed:
       return FaviconURL::TOUCH_PRECOMPOSED_ICON;
     case WebKit::WebIconURL::TypeInvalid:
       return FaviconURL::INVALID_ICON;
@@ skipping 253 matching lines @@
     CompleteInit();
   }
 
   g_view_map.Get().insert(std::make_pair(webview(), this));
   g_routing_id_view_map.Get().insert(std::make_pair(routing_id_, this));
   webview()->setDeviceScaleFactor(device_scale_factor_);
   webview()->settings()->setAcceleratedCompositingForFixedPositionEnabled(
       ShouldUseFixedPositionCompositing(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
       ShouldUseTransitionCompositing(device_scale_factor_));
+  webview()->settings()->setAcceleratedCompositingForFixedRootBackgroundEnabled(
+      ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
 
   webkit_glue::ApplyWebPreferences(webkit_preferences_, webview());
   webview()->initializeMainFrame(this);
 
   if (switches::IsTouchDragDropEnabled())
     webview()->settings()->setTouchDragDropEnabled(true);
 
   if (switches::IsTouchEditingEnabled())
     webview()->settings()->setTouchEditingEnabled(true);
 
@@ skipping 5299 matching lines @@
 }
 
 void RenderViewImpl::SetDeviceScaleFactor(float device_scale_factor) {
   RenderWidget::SetDeviceScaleFactor(device_scale_factor);
   if (webview()) {
     webview()->setDeviceScaleFactor(device_scale_factor);
     webview()->settings()->setAcceleratedCompositingForFixedPositionEnabled(
         ShouldUseFixedPositionCompositing(device_scale_factor_));
     webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
         ShouldUseTransitionCompositing(device_scale_factor_));
+    webview()->settings()->
+        setAcceleratedCompositingForFixedRootBackgroundEnabled(
+            ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
   }
   if (auto_resize_mode_)
     AutoResizeCompositor();
 
   if (browser_plugin_manager_.get())
     browser_plugin_manager_->UpdateDeviceScaleFactor(device_scale_factor_);
 }
 
 ui::TextInputType RenderViewImpl::GetTextInputType() {
   return pepper_helper_->IsPluginFocused() ?
@@ skipping 506 matching lines @@
     WebURL url = icon_urls[i].iconURL();
     if (!url.isEmpty())
       urls.push_back(FaviconURL(url,
                                 ToFaviconType(icon_urls[i].iconType())));
   }
   SendUpdateFaviconURL(urls);
 }
 
 
 }  // namespace content