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 7139f7eaecf7fffa109e80a92bbeebf69c9471cf..0eb872074b95ce98882f2d51ebf1ae057e6d3f68 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -1008,6 +1008,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
     cc::switches::kEnablePinchVirtualViewport,
     cc::switches::kEnableTopControlsPositionCalculation,
     cc::switches::kForceDirectLayerDrawing,
+    cc::switches::kForceSolidColorScrollbars,
     cc::switches::kLowResolutionContentsScaleFactor,
     cc::switches::kMaxTilesForInterestArea,
     cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
@@ -1021,6 +1022,8 @@ 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,