Plumb CompositingReason from Blink to compositor.

public/platform/WebCompositingReasons.h

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef WebCompositingReasons_h
+#define WebCompositingReasons_h
+
+// This define will go away after landing both chromium and blink sides.
+#define USE_WEB_COMPOSITING_REASONS 1

[jamesr, 2013/05/22 21:47:34]

hmm, not sure what purpose this serves. chromium code can't #include this header
until it exists, at which point it'll be in use.

+
+namespace WebKit {
+
+// This is a clone of CompositingReasons enum in RenderLayer.h,
+enum {
+    CompositingReasonUnknown                                = 0,
+    CompositingReason3DTransform                            = 1 << 0,
+    CompositingReasonVideo                                  = 1 << 1,
+    CompositingReasonCanvas                                 = 1 << 2,
+    CompositingReasonPlugin                                 = 1 << 3,
+    CompositingReasonIFrame                                 = 1 << 4,
+    CompositingReasonBackfaceVisibilityHidden               = 1 << 5,
+    CompositingReasonAnimation                              = 1 << 6,
+    CompositingReasonFilters                                = 1 << 7,
+    CompositingReasonPositionFixed                          = 1 << 8,
+    CompositingReasonPositionSticky                         = 1 << 9,
+    CompositingReasonOverflowScrollingTouch                 = 1 << 10,
+    CompositingReasonBlending                               = 1 << 11,
+    CompositingReasonAssumedOverlap                         = 1 << 12,
+    CompositingReasonOverlap                                = 1 << 13,
+    CompositingReasonNegativeZIndexChildren                 = 1 << 14,
+    CompositingReasonTransformWithCompositedDescendants     = 1 << 15,
+    CompositingReasonOpacityWithCompositedDescendants       = 1 << 16,
+    CompositingReasonMaskWithCompositedDescendants          = 1 << 17,
+    CompositingReasonReflectionWithCompositedDescendants    = 1 << 18,
+    CompositingReasonFilterWithCompositedDescendants        = 1 << 19,
+    CompositingReasonBlendingWithCompositedDescendants      = 1 << 20,
+    CompositingReasonClipsCompositingDescendants            = 1 << 21,
+    CompositingReasonPerspective                            = 1 << 22,
+    CompositingReasonPreserve3D                             = 1 << 23,
+    CompositingReasonReflectionOfCompositedParent           = 1 << 24,
+    CompositingReasonRoot                                   = 1 << 25,
+    CompositingReasonLayerForClip                           = 1 << 26,
+    CompositingReasonLayerForScrollbar                      = 1 << 27,
+    CompositingReasonLayerForScrollingContainer             = 1 << 28,
+    CompositingReasonLayerForForeground                     = 1 << 29,
+    CompositingReasonLayerForBackground                     = 1 << 30,
+    CompositingReasonLayerForMask                           = 1 << 31,
+};
+
+// It is a typedef to allow bitwise operators to be used without type casts.
+typedef unsigned WebCompositingReasons;
+
+} // namespace WebKit
+
+#endif // WebCompositingReasons_h