cc: Use FilterOperations::MapRect in RenderSurfaceImpl::DrawableContentRect.

cc/trees/layer_tree_host_common_unittest.cc

Index: cc/trees/layer_tree_host_common_unittest.cc
diff --git a/cc/trees/layer_tree_host_common_unittest.cc b/cc/trees/layer_tree_host_common_unittest.cc
index 2a2ca196f6278a3fd4e6a6584bc15eaa11e508b9..fa09f14f6eb73dbf56644d8c3dc67410f632afcb 100644
--- a/cc/trees/layer_tree_host_common_unittest.cc
+++ b/cc/trees/layer_tree_host_common_unittest.cc
@@ -46,6 +46,7 @@
 #include "cc/trees/task_runner_provider.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "third_party/skia/include/effects/SkOffsetImageFilter.h"
 #include "ui/gfx/geometry/quad_f.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 #include "ui/gfx/transform.h"
@@ -1411,6 +1412,33 @@ TEST_F(LayerTreeHostCommonTest, RenderSurfaceListForFilter) {
             parent->render_surface()->DrawableContentRect());
 }
 
+TEST_F(LayerTreeHostCommonTest, DrawableContentRectForReferenceFilter) {
+  LayerImpl* root = root_layer();
+  LayerImpl* child = AddChild<LayerImpl>(root);
+  child->SetDrawsContent(true);
+
+  SetLayerPropertiesForTesting(root, gfx::Transform(), gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(100, 100), true, false,
+                               true);
+  SetLayerPropertiesForTesting(child, gfx::Transform(), gfx::Point3F(),
+                               gfx::PointF(), gfx::Size(25, 25), true, false,
+                               true);
+
+  FilterOperations filters;
+  filters.Append(FilterOperation::CreateReferenceFilter(
+      SkOffsetImageFilter::Make(50, 50, nullptr)));
+  child->SetFilters(filters);
+
+  ExecuteCalculateDrawProperties(root);
+
+  // The render surface's size should be unaffected by the offset image filter;
+  // it need only have a drawable content rect large enough to contain the
+  // contents (at the new offset).
+  ASSERT_TRUE(child->render_surface());
+  EXPECT_EQ(gfx::RectF(50, 50, 25, 25),
+            child->render_surface()->DrawableContentRect());
+}
+
 TEST_F(LayerTreeHostCommonTest, RenderSurfaceForBlendMode) {
   LayerImpl* parent = root_layer();
   LayerImpl* child = AddChild<LayerImpl>(parent);