Revert of Reduce copying of local data structures in GeometryMapper and PaintLayerClipper.

third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h

Index: third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h b/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
index c5a8ec363590b631f85f1104088fa28416094cbc..9b1fff2b6638efb371ffc52789a749090fb94665 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/GeometryMapper.h
@@ -19,10 +19,6 @@
 // NOTE: A GeometryMapper object is only valid for property trees that do not
 // change. If any mutation occurs, a new GeometryMapper object must be allocated
 // corresponding to the new state.
-//
-// ** WARNING** Callers to the methods below may not assume that any const
-// references returned remain const across multiple calls into GeometryMapper.
-// If needed, callers must store local copies of the return values.
 //
 // Design document: http://bit.ly/28P4FDA
 //
@@ -48,20 +44,17 @@
   //
   // DCHECK fails if the clip of |destinationState| is not an ancestor of the
   // clip of |sourceState|, or the inverse transform is not invertible.
-  //
-  // |mappingRect| is both input and output.
-  void sourceToDestinationVisualRect(const PropertyTreeState& sourceState,
-                                     const PropertyTreeState& destinationState,
-                                     FloatRect& mappingRect);
+  FloatClipRect sourceToDestinationVisualRect(
+      const FloatRect&,
+      const PropertyTreeState& sourceState,
+      const PropertyTreeState& destinationState);
 
   // Same as sourceToDestinationVisualRect() except that only transforms are
   // applied.
-  //
-  // |mappingRect| is both input and output.
-  void sourceToDestinationRect(
+  FloatRect sourceToDestinationRect(
+      const FloatRect&,
       const TransformPaintPropertyNode* sourceTransformNode,
-      const TransformPaintPropertyNode* destinationTransformNode,
-      FloatRect& mappingRect);
+      const TransformPaintPropertyNode* destinationTransformNode);
 
   // Maps from a rect in |localTransformSpace| to its visual rect in
   // |ancestorState|. This is computed by multiplying the rect by its combined
@@ -75,11 +68,10 @@
   // DCHECK fails if any of the paint property tree nodes in
   // |localTransformState| are not equal to or a descendant of that in
   // |ancestorState|.
-  //
-  // |mappingRect| is both input and output.
-  void localToAncestorVisualRect(const PropertyTreeState& localTransformState,
-                                 const PropertyTreeState& ancestorState,
-                                 FloatRect& mappingRect);
+  FloatClipRect localToAncestorVisualRect(
+      const FloatRect&,
+      const PropertyTreeState& localTransformState,
+      const PropertyTreeState& ancestorState);
 
   // Maps from a rect in |localTransformNode| space to its transformed rect in
   // |ancestorTransformNode| space. This is computed by multiplying the rect by
@@ -88,12 +80,10 @@
   //
   // DCHECK fails if |localTransformNode| is not equal to or a descendant of
   // |ancestorTransformNode|.
-  //
-  //|mappingRect| is both input and output.
-  void localToAncestorRect(
+  FloatRect localToAncestorRect(
+      const FloatRect&,
       const TransformPaintPropertyNode* localTransformNode,
-      const TransformPaintPropertyNode* ancestorTransformNode,
-      FloatRect& mappingRect);
+      const TransformPaintPropertyNode* ancestorTransformNode);
 
   // Maps from a rect in |ancestorTransformNode| space to its transformed rect
   // in |localTransformNode| space. This is computed by multiplying the rect by
@@ -103,12 +93,10 @@
   // DCHECK fails if the combined transform is not invertible, or
   // |localTransformNode| is not equal to or a descendant of
   // |ancestorTransformNode|.
-  //
-  // |mappingRect| is both input and output.
-  void ancestorToLocalRect(
+  FloatRect ancestorToLocalRect(
+      const FloatRect&,
       const TransformPaintPropertyNode* ancestorTransformNode,
-      const TransformPaintPropertyNode* localTransformNode,
-      FloatRect& mappingRect);
+      const TransformPaintPropertyNode* localTransformNode);
 
   // Returns the matrix used in |LocalToAncestorRect|. DCHECK fails iff
   // |localTransformNode| is not equal to or a descendant of
@@ -125,7 +113,7 @@
 
   // Like localToAncestorClipRect, except it can handle destination transform
   // spaces which are not direct ancestors of the source transform space.
-  const FloatClipRect& sourceToDestinationClipRect(
+  FloatClipRect sourceToDestinationClipRect(
       const PropertyTreeState& sourceState,
       const PropertyTreeState& destinationState);
 
@@ -145,22 +133,22 @@
   // successful on return. See comments of the public functions for failure
   // conditions.
 
-  void sourceToDestinationVisualRectInternal(
+  FloatClipRect sourceToDestinationVisualRectInternal(
+      const FloatRect&,
       const PropertyTreeState& sourceState,
       const PropertyTreeState& destinationState,
-      FloatRect& mappingRect,
       bool& success);
 
-  void localToAncestorVisualRectInternal(
+  FloatClipRect localToAncestorVisualRectInternal(
+      const FloatRect&,
       const PropertyTreeState& localTransformState,
       const PropertyTreeState& ancestorState,
-      FloatRect& mappingRect,
       bool& success);
 
-  void localToAncestorRectInternal(
+  FloatRect localToAncestorRectInternal(
+      const FloatRect&,
       const TransformPaintPropertyNode* localTransformNode,
       const TransformPaintPropertyNode* ancestorTransformNode,
-      FloatRect&,
       bool& success);
 
   const TransformationMatrix& localToAncestorMatrixInternal(
@@ -174,25 +162,22 @@
       const TransformPaintPropertyNode* ancestorTransform,
       bool& success);
 
-  const FloatClipRect& sourceToDestinationClipRectInternal(
+  FloatClipRect sourceToDestinationClipRectInternal(
       const PropertyTreeState& sourceState,
       const PropertyTreeState& destinationState,
       bool& success);
 
-  void slowLocalToAncestorVisualRectWithEffects(
+  FloatClipRect slowLocalToAncestorVisualRectWithEffects(
+      const FloatRect&,
       const PropertyTreeState& localState,
       const PropertyTreeState& ancestorState,
-      FloatRect& mappingRect,
       bool& success);
 
   friend class GeometryMapperTest;
   friend class PaintLayerClipperTest;
 
-  // These are used to represent various return values of the above
-  // methods.
   const TransformationMatrix m_identity;
   const FloatClipRect m_infiniteClip;
-  FloatClipRect m_tempRect;
 
   DISALLOW_COPY_AND_ASSIGN(GeometryMapper);
 };