compositor-worker: Force elements to grow a layer when a CompositorProxy is created.

Source/platform/graphics/CompositingReasons.h

 // Copyright 2014 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 CompositingReasons_h
 #define CompositingReasons_h
 
 #include "platform/PlatformExport.h"
 #include "wtf/MathExtras.h"
 #include <stdint.h>
@@ skipping 70 matching lines @@
 const uint64_t CompositingReasonLayerForForeground                       = UINT64_C(1) << 54;
 const uint64_t CompositingReasonLayerForBackground                       = UINT64_C(1) << 55;
 const uint64_t CompositingReasonLayerForMask                             = UINT64_C(1) << 56;
 const uint64_t CompositingReasonLayerForClippingMask                     = UINT64_C(1) << 57;
 const uint64_t CompositingReasonLayerForScrollingBlockSelection          = UINT64_C(1) << 58;
 
 // Composited elements with inline transforms trigger assumed overlap so that
 // we can update their transforms quickly.
 const uint64_t CompositingReasonInlineTransform                          = UINT64_C(1) << 59;
 
+const uint64_t CompositingReasonCompositorProxy                          = UINT64_C(1) << 60;
+
 // Various combinations of compositing reasons are defined here also, for more intutive and faster bitwise logic.
 const uint64_t CompositingReasonComboAllDirectReasons =
     CompositingReason3DTransform
     | CompositingReasonVideo
     | CompositingReasonCanvas
     | CompositingReasonPlugin
     | CompositingReasonIFrame
     | CompositingReasonBackfaceVisibilityHidden
     | CompositingReasonActiveAnimation
     | CompositingReasonTransitionProperty
     | CompositingReasonPositionFixed
     | CompositingReasonOverflowScrollingTouch
     | CompositingReasonOverflowScrollingParent
     | CompositingReasonOutOfFlowClipping
     | CompositingReasonVideoOverlay
     | CompositingReasonWillChangeCompositingHint
-    | CompositingReasonScrollBlocksOn;
+    | CompositingReasonScrollBlocksOn
+    | CompositingReasonCompositorProxy;
 
 const uint64_t CompositingReasonComboAllDirectStyleDeterminedReasons =
     CompositingReason3DTransform
     | CompositingReasonBackfaceVisibilityHidden
     | CompositingReasonActiveAnimation
     | CompositingReasonTransitionProperty
     | CompositingReasonWillChangeCompositingHint
-    | CompositingReasonScrollBlocksOn;
+    | CompositingReasonScrollBlocksOn
+    | CompositingReasonCompositorProxy;
 
 const uint64_t CompositingReasonComboCompositedDescendants =
     CompositingReasonTransformWithCompositedDescendants
     | CompositingReasonIsolateCompositedDescendants
     | CompositingReasonOpacityWithCompositedDescendants
     | CompositingReasonMaskWithCompositedDescendants
     | CompositingReasonFilterWithCompositedDescendants
     | CompositingReasonBlendingWithCompositedDescendants
     | CompositingReasonReflectionWithCompositedDescendants
     | CompositingReasonClipsCompositingDescendants;
@@ skipping 58 matching lines @@
     const char* shortName;
     const char* description;
 };
 
 PLATFORM_EXPORT extern const CompositingReasonStringMap kCompositingReasonStringMap[];
 PLATFORM_EXPORT extern size_t kNumberOfCompositingReasons;
 
 } // namespace blink
 
 #endif // CompositingReasons_h