Add category handling to RasterWorkerPool

content/public/common/content_switches.cc

Index: content/public/common/content_switches.cc
diff --git a/content/public/common/content_switches.cc b/content/public/common/content_switches.cc
index b7d4010e1c5d394affd89e15c222e0779c070c22..496df0fd82671d3ecae18c94c4f4993195554159 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -825,6 +825,12 @@ const char kUseNormalPriorityForTileTaskWorkerThreads[] =
 // Use remote compositor for the renderer.
 const char kUseRemoteCompositing[] = "use-remote-compositing";
 
+// Causes all low-priority "background" raster tasks to run on a single thread,
+// reducing their likelihood of contending with higher priority tasks for system
+// resources.
+const char kUseSingleThreadForBackgroundRasterTasks[] =
+    "use-single-thread-for-background-raster-tasks";
+
 // Use the new surfaces system to handle compositor delegation.
 const char kUseSurfaces[] = "use-surfaces";