Improve the compositing reasons when squashing fails

Source/platform/graphics/CompositingReasons.h

Index: Source/platform/graphics/CompositingReasons.h
diff --git a/Source/platform/graphics/CompositingReasons.h b/Source/platform/graphics/CompositingReasons.h
index 3111cfa1c65f29d56af7dde3bd8c02063e096ba3..b72e78c8a0d7a6db7e625dfd06c9ed999dad902f 100644
--- a/Source/platform/graphics/CompositingReasons.h
+++ b/Source/platform/graphics/CompositingReasons.h
@@ -36,40 +36,47 @@ const uint64_t CompositingReasonWillChangeCompositingHint              = UINT64_
 const uint64_t CompositingReasonAssumedOverlap                         = UINT64_C(1) << 17;
 const uint64_t CompositingReasonOverlap                                = UINT64_C(1) << 18;
 const uint64_t CompositingReasonNegativeZIndexChildren                 = UINT64_C(1) << 19;
-const uint64_t CompositingReasonNoSquashingTargetFound                 = UINT64_C(1) << 20;
+const uint64_t CompositingReasonScrollsWithRespectToSquashingLayer     = UINT64_C(1) << 20;
+const uint64_t CompositingReasonSquashingSparsityExceeded              = UINT64_C(1) << 21;
+const uint64_t CompositingReasonSquashingClippingContainerMismatch     = UINT64_C(1) << 22;
+const uint64_t CompositingReasonSquashingOpacityAncestorMismatch       = UINT64_C(1) << 23;
+const uint64_t CompositingReasonSquashingTransformAncestorMismatch     = UINT64_C(1) << 24;
+const uint64_t CompositingReasonSquashingFilterAncestorMismatch        = UINT64_C(1) << 25;
+const uint64_t CompositingReasonSquashingWouldBreakPaintOrder          = UINT64_C(1) << 26;
+const uint64_t CompositingReasonSquashingVideoIsDisallowed             = UINT64_C(1) << 27;
 
 // Subtree reasons that require knowing what the status of your subtree is before knowing the answer
-const uint64_t CompositingReasonTransformWithCompositedDescendants     = UINT64_C(1) << 21;
-const uint64_t CompositingReasonOpacityWithCompositedDescendants       = UINT64_C(1) << 22;
-const uint64_t CompositingReasonMaskWithCompositedDescendants          = UINT64_C(1) << 23;
-const uint64_t CompositingReasonReflectionWithCompositedDescendants    = UINT64_C(1) << 24;
-const uint64_t CompositingReasonFilterWithCompositedDescendants        = UINT64_C(1) << 25;
-const uint64_t CompositingReasonBlendingWithCompositedDescendants      = UINT64_C(1) << 26;
-const uint64_t CompositingReasonClipsCompositingDescendants            = UINT64_C(1) << 27;
-const uint64_t CompositingReasonPerspectiveWith3DDescendants           = UINT64_C(1) << 28;
-const uint64_t CompositingReasonPreserve3DWith3DDescendants            = UINT64_C(1) << 29;
-const uint64_t CompositingReasonReflectionOfCompositedParent           = UINT64_C(1) << 30;
-const uint64_t CompositingReasonIsolateCompositedDescendants           = UINT64_C(1) << 31;
+const uint64_t CompositingReasonTransformWithCompositedDescendants     = UINT64_C(1) << 28;
+const uint64_t CompositingReasonOpacityWithCompositedDescendants       = UINT64_C(1) << 29;
+const uint64_t CompositingReasonMaskWithCompositedDescendants          = UINT64_C(1) << 30;
+const uint64_t CompositingReasonReflectionWithCompositedDescendants    = UINT64_C(1) << 31;
+const uint64_t CompositingReasonFilterWithCompositedDescendants        = UINT64_C(1) << 32;
+const uint64_t CompositingReasonBlendingWithCompositedDescendants      = UINT64_C(1) << 33;
+const uint64_t CompositingReasonClipsCompositingDescendants            = UINT64_C(1) << 34;
+const uint64_t CompositingReasonPerspectiveWith3DDescendants           = UINT64_C(1) << 35;
+const uint64_t CompositingReasonPreserve3DWith3DDescendants            = UINT64_C(1) << 36;
+const uint64_t CompositingReasonReflectionOfCompositedParent           = UINT64_C(1) << 37;
+const uint64_t CompositingReasonIsolateCompositedDescendants           = UINT64_C(1) << 38;
 
 // The root layer is a special case that may be forced to be a layer, but also it needs to be
 // a layer if anything else in the subtree is composited.
-const uint64_t CompositingReasonRoot                                   = UINT64_C(1) << 32;
+const uint64_t CompositingReasonRoot                                   = UINT64_C(1) << 39;
 
 // CompositedLayerMapping internal hierarchy reasons
-const uint64_t CompositingReasonLayerForAncestorClip                   = UINT64_C(1) << 33;
-const uint64_t CompositingReasonLayerForDescendantClip                 = UINT64_C(1) << 34;
-const uint64_t CompositingReasonLayerForPerspective                    = UINT64_C(1) << 35;
-const uint64_t CompositingReasonLayerForHorizontalScrollbar            = UINT64_C(1) << 36;
-const uint64_t CompositingReasonLayerForVerticalScrollbar              = UINT64_C(1) << 37;
-const uint64_t CompositingReasonLayerForScrollCorner                   = UINT64_C(1) << 38;
-const uint64_t CompositingReasonLayerForScrollingContents              = UINT64_C(1) << 39;
-const uint64_t CompositingReasonLayerForScrollingContainer             = UINT64_C(1) << 40;
-const uint64_t CompositingReasonLayerForSquashingContents              = UINT64_C(1) << 41;
-const uint64_t CompositingReasonLayerForSquashingContainer             = UINT64_C(1) << 42;
-const uint64_t CompositingReasonLayerForForeground                     = UINT64_C(1) << 43;
-const uint64_t CompositingReasonLayerForBackground                     = UINT64_C(1) << 44;
-const uint64_t CompositingReasonLayerForMask                           = UINT64_C(1) << 45;
-const uint64_t CompositingReasonLayerForClippingMask                   = UINT64_C(1) << 46;
+const uint64_t CompositingReasonLayerForAncestorClip                   = UINT64_C(1) << 40;
+const uint64_t CompositingReasonLayerForDescendantClip                 = UINT64_C(1) << 41;
+const uint64_t CompositingReasonLayerForPerspective                    = UINT64_C(1) << 42;
+const uint64_t CompositingReasonLayerForHorizontalScrollbar            = UINT64_C(1) << 43;
+const uint64_t CompositingReasonLayerForVerticalScrollbar              = UINT64_C(1) << 44;
+const uint64_t CompositingReasonLayerForScrollCorner                   = UINT64_C(1) << 45;
+const uint64_t CompositingReasonLayerForScrollingContents              = UINT64_C(1) << 46;
+const uint64_t CompositingReasonLayerForScrollingContainer             = UINT64_C(1) << 47;
+const uint64_t CompositingReasonLayerForSquashingContents              = UINT64_C(1) << 48;
+const uint64_t CompositingReasonLayerForSquashingContainer             = UINT64_C(1) << 49;
+const uint64_t CompositingReasonLayerForForeground                     = UINT64_C(1) << 50;
+const uint64_t CompositingReasonLayerForBackground                     = UINT64_C(1) << 51;
+const uint64_t CompositingReasonLayerForMask                           = UINT64_C(1) << 52;
+const uint64_t CompositingReasonLayerForClippingMask                   = UINT64_C(1) << 53;
 
 // Various combinations of compositing reasons are defined here also, for more intutive and faster bitwise logic.
 const uint64_t CompositingReasonComboAllDirectReasons =
@@ -102,7 +109,14 @@ const uint64_t CompositingReasonComboReasonsThatRequireOwnBacking =
     | CompositingReasonOverlap
     | CompositingReasonAssumedOverlap
     | CompositingReasonNegativeZIndexChildren
-    | CompositingReasonNoSquashingTargetFound
+    | CompositingReasonScrollsWithRespectToSquashingLayer
+    | CompositingReasonSquashingSparsityExceeded
+    | CompositingReasonSquashingClippingContainerMismatch
+    | CompositingReasonSquashingOpacityAncestorMismatch
+    | CompositingReasonSquashingTransformAncestorMismatch
+    | CompositingReasonSquashingFilterAncestorMismatch
+    | CompositingReasonSquashingWouldBreakPaintOrder
+    | CompositingReasonSquashingVideoIsDisallowed
     | CompositingReasonTransformWithCompositedDescendants
     | CompositingReasonOpacityWithCompositedDescendants
     | CompositingReasonMaskWithCompositedDescendants
@@ -198,9 +212,30 @@ static const CompositingReasonStringMap compositingReasonStringMap[] = {
     { CompositingReasonNegativeZIndexChildren,
         "negativeZIndexChildren",
         "Parent with composited negative z-index content" },
-    {  CompositingReasonNoSquashingTargetFound,
-        "noSquashingTargetFound",
-        "Cannot be squashed due to no compatible squashing owner found" },
+    { CompositingReasonScrollsWithRespectToSquashingLayer,
+        "scrollsWithRespectToSquashingLayer",
+        "Cannot be squashed since this layer scrolls with respect to the squashing layer" },
+    { CompositingReasonSquashingSparsityExceeded,
+        "squashingSparsityExceeded",
+        "Cannot be squashed as the squashing layer would become too sparse" },
+    { CompositingReasonSquashingClippingContainerMismatch,
+        "squashingClippingContainerMismatch",
+        "Cannot be squashed because this layer has a different clipping container than the squashing layer" },
+    { CompositingReasonSquashingOpacityAncestorMismatch,
+        "squashingOpacityAncestorMismatch",
+        "Cannot be squashed because this layer has a different opacity ancestor than the squashing layer" },
+    { CompositingReasonSquashingTransformAncestorMismatch,
+        "squashingTransformAncestorMismatch",
+        "Cannot be squashed because this layer has a different transform ancestor than the squashing layer" },
+    { CompositingReasonSquashingFilterAncestorMismatch,
+        "squashingFilterAncestorMismatch",
+        "Cannot be squashed because this layer has a different filter ancestor than the squashing layer" },
+    { CompositingReasonSquashingWouldBreakPaintOrder,
+        "squashingWouldBreakPaintOrder",
+        "Cannot be squashed without breaking paint order" },
+    { CompositingReasonSquashingVideoIsDisallowed,
+        "squashingVideoIsDisallowed",
+        "Squashing video is not supported" },
     { CompositingReasonTransformWithCompositedDescendants,
         "transformWithCompositedDescendants",
         "Has a transform that needs to be known by compositor because of composited descendants" },