Clip related property and border radius are now recorded for UMA

cc/input/main_thread_scrolling_reason.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_
 #define CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_
 
 #include <string>
 
 #include "base/trace_event/trace_event_argument.h"
@@ skipping 13 matching lines @@
     kScrollbarScrolling = 1 << 3,
     kPageOverlay = 1 << 4,
 
     // This bit is set when any of the other main thread scrolling reasons cause
     // an input event to be handled on the main thread, and the main thread
     // blink::ScrollAnimator is in the middle of running a scroll offset
     // animation. Note that a scroll handled by the main thread can result in an
     // 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,
     kFailedHitTest = 1 << 7,
     kNoScrollingLayer = 1 << 8,
     kNotScrollable = 1 << 9,
     kContinuingMainThreadScroll = 1 << 10,
     kNonInvertibleTransform = 1 << 11,
     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
   // thread.
   static bool MainThreadCanSetScrollReasons(uint32_t reasons) {
     uint32_t reasons_set_by_main_thread =
         kNotScrollingOnMain | kHasBackgroundAttachmentFixedObjects |
         kHasNonLayerViewportConstrainedObjects | kThreadedScrollingDisabled |
         kScrollbarScrolling | kPageOverlay | kHandlingScrollFromMainThread |
         kCustomScrollbarScrolling | kHasOpacity | kHasTransform |
-        kBackgroundNotOpaqueInRect;
+        kBackgroundNotOpaqueInRect | kHasBorderRadius | kHasClipRelatedProperty;
     return (reasons & reasons_set_by_main_thread) == reasons;
   }
 
   // Returns true if the given MainThreadScrollingReason can be set by the
   // compositor.
   static bool CompositorCanSetScrollReasons(uint32_t reasons) {
     uint32_t reasons_set_by_compositor =
         kNonFastScrollableRegion | kFailedHitTest | kNoScrollingLayer |
         kNotScrollable | kContinuingMainThreadScroll | kNonInvertibleTransform |
         kPageBasedScrolling;
@@ skipping 30 matching lines @@
     if (reasons & MainThreadScrollingReason::kHandlingScrollFromMainThread)
       tracedValue->AppendString("Handling scroll from main thread");
     if (reasons & MainThreadScrollingReason::kCustomScrollbarScrolling)
       tracedValue->AppendString("Custom scrollbar scrolling");
     if (reasons & MainThreadScrollingReason::kHasOpacity)
       tracedValue->AppendString("Has opacity");
     if (reasons & MainThreadScrollingReason::kHasTransform)
       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)
       tracedValue->AppendString("Non fast scrollable region");
     if (reasons & MainThreadScrollingReason::kFailedHitTest)
       tracedValue->AppendString("Failed hit test");
     if (reasons & MainThreadScrollingReason::kNoScrollingLayer)
       tracedValue->AppendString("No scrolling layer");
     if (reasons & MainThreadScrollingReason::kNotScrollable)
       tracedValue->AppendString("Not scrollable");
@@ skipping 17 matching lines @@
       reason = reason >> 1;
       ++index;
     }
     return index;
   }
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_MAIN_THREAD_SCROLLING_REASON_H_