Revert of Remove the acclerated overflow scroll and fixed root background flags.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 7b9ea0bba89272587081549b1a60ae56a64d09bc..63b77c78387e0efe10893485302d181586a5ccf5 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -408,6 +408,19 @@
   return DeviceScaleEnsuresTextQuality(device_scale_factor);
 }
 
+static bool ShouldUseAcceleratedCompositingForOverflowScroll(
+    float device_scale_factor) {
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+
+  if (command_line.HasSwitch(switches::kDisableAcceleratedOverflowScroll))
+    return false;
+
+  if (command_line.HasSwitch(switches::kEnableAcceleratedOverflowScroll))
+    return true;
+
+  return DeviceScaleEnsuresTextQuality(device_scale_factor);
+}
+
 static bool ShouldUseCompositedScrollingForFrames(
     float device_scale_factor) {
   if (RenderThreadImpl::current() &&
@@ -430,6 +443,18 @@
   // of excessive layer promotion caused by overlap has been addressed.
   // http://crbug.com/178119.
   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(blink::WebIconURL::Type type) {
@@ -769,11 +794,11 @@
   webview()->settings()->setPreferCompositingToLCDTextEnabled(
       PreferCompositingToLCDText(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForOverflowScrollEnabled(
-      PreferCompositingToLCDText(device_scale_factor_));
+      ShouldUseAcceleratedCompositingForOverflowScroll(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
       ShouldUseTransitionCompositing(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForFixedRootBackgroundEnabled(
-      PreferCompositingToLCDText(device_scale_factor_));
+      ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
   webview()->settings()->setCompositedScrollingForFramesEnabled(
       ShouldUseCompositedScrollingForFrames(device_scale_factor_));
 
@@ -3741,13 +3766,12 @@
     webview()->settings()->setPreferCompositingToLCDTextEnabled(
         PreferCompositingToLCDText(device_scale_factor_));
     webview()->settings()->setAcceleratedCompositingForOverflowScrollEnabled(
-        PreferCompositingToLCDText(device_scale_factor_));
+        ShouldUseAcceleratedCompositingForOverflowScroll(device_scale_factor_));
     webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
         ShouldUseTransitionCompositing(device_scale_factor_));
-    webview()
-        ->settings()
-        ->setAcceleratedCompositingForFixedRootBackgroundEnabled(
-            PreferCompositingToLCDText(device_scale_factor_));
+    webview()->settings()->
+        setAcceleratedCompositingForFixedRootBackgroundEnabled(
+            ShouldUseAcceleratedFixedRootBackground(device_scale_factor_));
     webview()->settings()->setCompositedScrollingForFramesEnabled(
         ShouldUseCompositedScrollingForFrames(device_scale_factor_));
   }