Add a new flag for slimming paint invalidation

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 09a17d465e08006a085a4398d3dfe10736e1f923..f1f8a0b148c2f333c8c955dd3cc960c5532806f2 100644
--- a/content/public/common/content_switches.cc
+++ b/content/public/common/content_switches.cc
@@ -459,6 +459,11 @@ const char kEnableSkiaBenchmarking[]        = "enable-skia-benchmarking";
 // Enables slimming paint phase 2: http://www.chromium.org/blink/slimming-paint
 const char kEnableSlimmingPaintV2[]         = "enable-slimming-paint-v2";
 
+// Enables paint invalidation based on slimming paint but without the full
+// slimming paint v2 compositing code. See: https://goo.gl/eQczQW
+const char kEnableSlimmingPaintInvalidation[] =
+    "enable-slimming-paint-invalidation";
+
 // On platforms that support it, enables smooth scroll animation.
 const char kEnableSmoothScrolling[]         = "enable-smooth-scrolling";