Make IsSolidColor() a property on CC scrollbar layers.

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 03f28d771ece431eae9cd1ac660bfa5b8dcda2cd..2a416f212f2c4897c5d71e084712650a143527f2 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1014,6 +1014,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     cc::switches::kEnablePinchVirtualViewport,
     cc::switches::kEnableTopControlsPositionCalculation,
     cc::switches::kForceDirectLayerDrawing,
+    cc::switches::kForceSolidColorScrollbars,
     cc::switches::kLowResolutionContentsScaleFactor,
     cc::switches::kMaxTilesForInterestArea,
     cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
@@ -1027,6 +1028,8 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     cc::switches::kShowScreenSpaceRects,
     cc::switches::kShowSurfaceDamageRects,
     cc::switches::kSlowDownRasterScaleFactor,
+    cc::switches::kSolidColorScrollbarColor,
+    cc::switches::kSolidColorScrollbarThickness,
     cc::switches::kStrictLayerPropertyChangeChecking,
     cc::switches::kTopControlsHeight,
     cc::switches::kTopControlsHideThreshold,