Chromium side plumbing for enabling fixed root background compositing.

Adds --enable-accelerated-fixed-root-background and related plumbing.

Depends on wkb.ug/112865

TBR=sky@chromium.org

BUG=180885

Review URL: https://chromiumcodereview.appspot.com/12544030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@210416 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 17 insertions, 0 deletions

diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 98c2b69..64a907c 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -619,6 +619,18 @@ static bool ShouldUseTransitionCompositing(float device_scale_factor) {
   return false;
 }
 
+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:
@@ -898,6 +910,8 @@ void RenderViewImpl::Initialize(RenderViewImplParams* params) {
       ShouldUseAcceleratedCompositingForOverflowScroll(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(main_render_frame_.get());
@@ -6246,6 +6260,9 @@ void RenderViewImpl::SetDeviceScaleFactor(float device_scale_factor) {
       ShouldUseAcceleratedCompositingForOverflowScroll(device_scale_factor_));
     webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
         ShouldUseTransitionCompositing(device_scale_factor_));
+    webview()->settings()->
+        setAcceleratedCompositingForFixedRootBackgroundEnabled(
+            ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
   }
   if (auto_resize_mode_)
     AutoResizeCompositor();