Scale the ALPHA_THRESHOLD filter's region based on the device scale factor.

cc/output/filter_operation.cc

 // Copyright 2013 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.
 
 #include <algorithm>
 
 #include "base/values.h"
 #include "cc/base/math_util.h"
 #include "cc/output/filter_operation.h"
 #include "third_party/skia/include/core/SkMath.h"
@@ skipping 231 matching lines @@
     blended_filter.set_zoom_inset(
         std::max(gfx::Tween::LinearIntValueBetween(
                      from_op.zoom_inset(), to_op.zoom_inset(), progress),
                  0));
   } else if (to_op.type() == FilterOperation::ALPHA_THRESHOLD) {
     blended_filter.set_outer_threshold(ClampAmountForFilterType(
             gfx::Tween::FloatValueBetween(progress,
                                           from_op.outer_threshold(),
                                           to_op.outer_threshold()),
             to_op.type()));
-    blended_filter.set_region(to_op.region());
+    const FilterOperation& copy_op = progress > 0.5 ? to_op : from_op;

[danakj, 2014/07/11 16:08:22]

is this needed?

+    blended_filter.set_region(copy_op.region());
   }
 
   return blended_filter;
 }
 
 scoped_ptr<base::Value> FilterOperation::AsValue() const {
   scoped_ptr<base::DictionaryValue> value(new base::DictionaryValue);
   value->SetInteger("type", type_);
   switch (type_) {
     case FilterOperation::GRAYSCALE:
@@ skipping 47 matching lines @@
           region_value->AppendInteger(it.rect().height());
         }
         value->Set("region", region_value.release());
       }
       break;
   }
   return value.PassAs<base::Value>();
 }
 
 }  // namespace cc