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

cc/output/filter_operation.cc

Index: cc/output/filter_operation.cc
diff --git a/cc/output/filter_operation.cc b/cc/output/filter_operation.cc
index 7682853b2e29f202085ee191965e22a503c75986..44f471308227c6f137e492c85ec913519f6a3d71 100644
--- a/cc/output/filter_operation.cc
+++ b/cc/output/filter_operation.cc
@@ -26,8 +26,9 @@ bool FilterOperation::operator==(const FilterOperation& other) const {
     return image_filter_.get() == other.image_filter_.get();
   if (type_ == ALPHA_THRESHOLD) {
     return region_ == other.region_ &&
-        amount_ == other.amount_ &&
-        outer_threshold_ == other.outer_threshold_;
+           device_scale_factor_ == other.device_scale_factor_ &&
+           amount_ == other.amount_ &&
+           outer_threshold_ == other.outer_threshold_;
   }
   return amount_ == other.amount_;
 }
@@ -38,7 +39,8 @@ FilterOperation::FilterOperation(FilterType type, float amount)
       outer_threshold_(0),
       drop_shadow_offset_(0, 0),
       drop_shadow_color_(0),
-      zoom_inset_(0) {
+      zoom_inset_(0),
+      device_scale_factor_(1.f) {
   DCHECK_NE(type_, DROP_SHADOW);
   DCHECK_NE(type_, COLOR_MATRIX);
   DCHECK_NE(type_, REFERENCE);
@@ -54,7 +56,8 @@ FilterOperation::FilterOperation(FilterType type,
       outer_threshold_(0),
       drop_shadow_offset_(offset),
       drop_shadow_color_(color),
-      zoom_inset_(0) {
+      zoom_inset_(0),
+      device_scale_factor_(1.f) {
   DCHECK_EQ(type_, DROP_SHADOW);
   memset(matrix_, 0, sizeof(matrix_));
 }
@@ -65,7 +68,8 @@ FilterOperation::FilterOperation(FilterType type, SkScalar matrix[20])
       outer_threshold_(0),
       drop_shadow_offset_(0, 0),
       drop_shadow_color_(0),
-      zoom_inset_(0) {
+      zoom_inset_(0),
+      device_scale_factor_(1.f) {
   DCHECK_EQ(type_, COLOR_MATRIX);
   memcpy(matrix_, matrix, sizeof(matrix_));
 }
@@ -76,7 +80,8 @@ FilterOperation::FilterOperation(FilterType type, float amount, int inset)
       outer_threshold_(0),
       drop_shadow_offset_(0, 0),
       drop_shadow_color_(0),
-      zoom_inset_(inset) {
+      zoom_inset_(inset),
+      device_scale_factor_(1.f) {
   DCHECK_EQ(type_, ZOOM);
   memset(matrix_, 0, sizeof(matrix_));
 }
@@ -90,13 +95,15 @@ FilterOperation::FilterOperation(
       drop_shadow_offset_(0, 0),
       drop_shadow_color_(0),
       image_filter_(image_filter),
-      zoom_inset_(0) {
+      zoom_inset_(0),
+      device_scale_factor_(1.f) {
   DCHECK_EQ(type_, REFERENCE);
   memset(matrix_, 0, sizeof(matrix_));
 }
 
 FilterOperation::FilterOperation(FilterType type,
                                  const SkRegion& region,
+                                 float device_scale_factor,
                                  float inner_threshold,
                                  float outer_threshold)
     : type_(type),
@@ -105,7 +112,8 @@ FilterOperation::FilterOperation(FilterType type,
       drop_shadow_offset_(0, 0),
       drop_shadow_color_(0),
       zoom_inset_(0),
-      region_(region) {
+      region_(region),
+      device_scale_factor_(device_scale_factor) {
   DCHECK_EQ(type_, ALPHA_THRESHOLD);
   memset(matrix_, 0, sizeof(matrix_));
 }
@@ -118,7 +126,8 @@ FilterOperation::FilterOperation(const FilterOperation& other)
       drop_shadow_color_(other.drop_shadow_color_),
       image_filter_(other.image_filter_),
       zoom_inset_(other.zoom_inset_),
-      region_(other.region_) {
+      region_(other.region_),
+      device_scale_factor_(other.device_scale_factor_) {
   memcpy(matrix_, other.matrix_, sizeof(matrix_));
 }
 
@@ -162,7 +171,8 @@ static FilterOperation CreateNoOpFilter(FilterOperation::FilterType type) {
       return FilterOperation::CreateReferenceFilter(
           skia::RefPtr<SkImageFilter>());
     case FilterOperation::ALPHA_THRESHOLD:
-      return FilterOperation::CreateAlphaThresholdFilter(SkRegion(), 1.f, 0.f);
+      return FilterOperation::CreateAlphaThresholdFilter(
+          SkRegion(), 1.f, 1.f, 0.f);
   }
   NOTREACHED();
   return FilterOperation::CreateEmptyFilter();
@@ -249,7 +259,9 @@ FilterOperation FilterOperation::Blend(const FilterOperation* from,
                                           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;
+    blended_filter.set_region(copy_op.region());
+    blended_filter.set_device_scale_factor(copy_op.device_scale_factor());
   }
 
   return blended_filter;
@@ -310,6 +322,7 @@ scoped_ptr<base::Value> FilterOperation::AsValue() const {
           region_value->AppendInteger(it.rect().height());
         }
         value->Set("region", region_value.release());
+        value->SetDouble("device_scale_factor", device_scale_factor_);
       }
       break;
   }