Plumb preferred raster scale for background images from Blink to cc layers.

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

Index: third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in
diff --git a/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in b/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in
index 6e9a3431660466bc80446477408677ee70a8e75a..ea0e5730921cc9284a08102099a4f5ea2a54b245 100644
--- a/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in
+++ b/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in
@@ -178,6 +178,7 @@ PointerEventV1SpecCapturing
 PreciseMemoryInfo
 // This feature is deprecated and we are evangelizing affected sites.
 // See https://crbug.com/346236 for current status.
+PreferredImageRasterScale settable_from_internals=True
 PrefixedVideoFullscreen status=stable
 Presentation status=stable
 PresentationReceiver status=test
@@ -259,4 +260,4 @@ WebFontsInterventionTrigger
 WebShare status=experimental, origin_trial_feature_name=WebShare, origin_trial_os=android
 Worklet status=experimental
 ParseHTMLOnMainThread status=test
-SendBeaconThrowForBlobWithNonSimpleType status=experimental
+SendBeaconThrowForBlobWithNonSimpleType status=experimental