cc: Add command line switch to control resource usage for impl-side painting.

cc/base/switches.cc

Index: cc/base/switches.cc
diff --git a/cc/base/switches.cc b/cc/base/switches.cc
index 86b10b1a12c9bd82ed69ee4846bf995066861f66..3e474cad3b4c4380553ca2248f7b04db01e2f59f 100644
--- a/cc/base/switches.cc
+++ b/cc/base/switches.cc
@@ -76,6 +76,10 @@ const char kMaxPrepaintTileDistance[] = "max-prepaint-tile-distance";
 // Max tiles allowed for each tilings interest area.
 const char kMaxTilesForInterestArea[] = "max-tiles-for-interest-area";
 
+// The amount of unused resource memory compositor is allowed to keep around.
+const char kMaxUnusedResourceMemoryUsagePercentage[] =
+    "max-unused-resource-memory-usage-percentage";
+
 // Causes the compositor to render to textures which are then sent to the parent
 // through the texture mailbox mechanism.
 // Requires --enable-compositor-frame-message.