Clip related property and border radius are now recorded for UMA

cc/input/main_thread_scrolling_reason.h

Index: cc/input/main_thread_scrolling_reason.h
diff --git a/cc/input/main_thread_scrolling_reason.h b/cc/input/main_thread_scrolling_reason.h
index 85a8ea117b7f1df92bf94ec792e3993599026bc6..31ed7eca67dc3b08e353d15b844b20423589efd1 100644
--- a/cc/input/main_thread_scrolling_reason.h
+++ b/cc/input/main_thread_scrolling_reason.h
@@ -31,9 +31,13 @@ struct MainThreadScrollingReason {
     // animation running on the main thread or on the compositor thread.
     kHandlingScrollFromMainThread = 1 << 13,
     kCustomScrollbarScrolling = 1 << 15,
+
+    // Style Related scrolling on main reasons
     kHasOpacity = 1 << 16,
     kHasTransform = 1 << 17,
     kBackgroundNotOpaqueInRect = 1 << 18,
+    kHasBorderRadius = 1 << 19,
+    kHasClipRelatedProperty = 1 << 20,
 
     // Transient scrolling reasons. These are computed for each scroll begin.
     kNonFastScrollableRegion = 1 << 5,
@@ -45,7 +49,7 @@ struct MainThreadScrollingReason {
     kPageBasedScrolling = 1 << 12,
 
     // The number of flags in this struct (excluding itself).

[bokan, 2017/01/05 14:05:48]

Please update this comment to describe the foot cannon that is this count value.
It's not the count of values, but the maximum shift + 2 because the loop in
InputHandlerProxy::RecordMainThreadScrollingReasons is wrong. If you could,
fixing the uses of this count value and renaming it to
kMainThreadScrollingReasonMaxValue (so that in this case it would be 1<<20 in a
followup patch would be great.

[yigu, 2017/01/05 14:46:50]

Done.

-    kMainThreadScrollingReasonCount = 20,
+    kMainThreadScrollingReasonCount = 22,
   };
 
   // Returns true if the given MainThreadScrollingReason can be set by the main
@@ -56,7 +60,7 @@ struct MainThreadScrollingReason {
         kHasNonLayerViewportConstrainedObjects | kThreadedScrollingDisabled |
         kScrollbarScrolling | kPageOverlay | kHandlingScrollFromMainThread |
         kCustomScrollbarScrolling | kHasOpacity | kHasTransform |
-        kBackgroundNotOpaqueInRect;
+        kBackgroundNotOpaqueInRect | kHasBorderRadius | kHasClipRelatedProperty;
     return (reasons & reasons_set_by_main_thread) == reasons;
   }
 
@@ -107,6 +111,10 @@ struct MainThreadScrollingReason {
       tracedValue->AppendString("Has transform");
     if (reasons & MainThreadScrollingReason::kBackgroundNotOpaqueInRect)
       tracedValue->AppendString("Background is not opaque in rect");
+    if (reasons & MainThreadScrollingReason::kHasBorderRadius)
+      tracedValue->AppendString("Has border radius");
+    if (reasons & MainThreadScrollingReason::kHasClipRelatedProperty)
+      tracedValue->AppendString("Has clip related property");
 
     // Transient scrolling reasons.
     if (reasons & MainThreadScrollingReason::kNonFastScrollableRegion)