Changes subtreeShouldRenderToSeparateSurface logic to account for explicit clipping

ui/gfx/transform.h

 // Copyright (c) 2012 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 UI_GFX_TRANSFORM_H_
 #define UI_GFX_TRANSFORM_H_
 
 #include "base/compiler_specific.h"
 #include "third_party/skia/include/utils/SkMatrix44.h"
 #include "ui/base/ui_export.h"
@@ skipping 60 matching lines @@
   void ConcatTransform(const Transform& transform);
 
   // Returns true if this is the identity matrix.
   bool IsIdentity() const { return matrix_.isIdentity(); }
 
   // Returns true if the matrix is either identity or pure translation.
   bool IsIdentityOrTranslation() const {
     return !(matrix_.getType() & ~SkMatrix44::kTranslate_Mask);
   }
 
+  // Returns trus if the matrix is either a scale and/or translation
+  bool IsPositiveScaleOrTranslation() const {

[danakj, 2012/12/15 18:49:12]

Could you add a unit test in ui/gfx/transform_unittest.cc please?

+    if (!IsScaleOrTranslation())
+      return false;
+    return matrix_.getDouble(0, 0) > 0.0 &&
+        matrix_.getDouble(1, 1) > 0.0 &&
+        matrix_.getDouble(2, 2) > 0.0;
+  }
+
   // Returns true if the matrix is either identity or pure, non-fractional
   // translation.
   bool IsIdentityOrIntegerTranslation() const;
 
   // Returns true if the matrix is has only scaling and translation components.
   bool IsScaleOrTranslation() const;
 
   // Returns true if the matrix has any perspective component that would
   // change the w-component of a homogeneous point.
   bool HasPerspective() const;
@@ skipping 69 matching lines @@
                               Point3F& point) const;
 
   SkMatrix44 matrix_;
 
   // copy/assign are allowed.
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_TRANSFORM_H_