3 files changed, 52 insertions, 5 deletions

diff --git a/cc/layers/surface_layer.cc b/cc/layers/surface_layer.cc
index f1909b4..ee376aa 100644
--- a/cc/layers/surface_layer.cc
+++ b/cc/layers/surface_layer.cc
@@ -53,9 +53,10 @@ SurfaceLayer::~SurfaceLayer() {
   DCHECK(destroy_sequence_.is_null());
 }
 
-void SurfaceLayer::SetSurfaceId(SurfaceId surface_id) {
+void SurfaceLayer::SetSurfaceId(SurfaceId surface_id, const gfx::Size& size) {
   SatisfyDestroySequence();
   surface_id_ = surface_id;
+  surface_size_ = size;
   CreateNewDestroySequence();
 
   UpdateDrawsContent(HasDrawableContent());
@@ -88,6 +89,19 @@ void SurfaceLayer::PushPropertiesTo(LayerImpl* layer) {
   layer_impl->SetSurfaceId(surface_id_);
 }
 
+void SurfaceLayer::CalculateContentsScale(float ideal_contents_scale,
+                                          float* contents_scale_x,
+                                          float* contents_scale_y,
+                                          gfx::Size* content_bounds) {
+  *content_bounds = surface_size_;
+  *contents_scale_x =
+      bounds().IsEmpty() ? 1.f : static_cast<float>(content_bounds->width()) /
+                                     bounds().width();
+  *contents_scale_y =
+      bounds().IsEmpty() ? 1.f : static_cast<float>(content_bounds->height()) /
+                                     bounds().height();
+}
+
 void SurfaceLayer::CreateNewDestroySequence() {
   DCHECK(destroy_sequence_.is_null());
   if (layer_tree_host()) {
diff --git a/cc/layers/surface_layer.h b/cc/layers/surface_layer.h
index 4292549..29d821f 100644
--- a/cc/layers/surface_layer.h
+++ b/cc/layers/surface_layer.h
@@ -9,6 +9,7 @@
 #include "cc/layers/layer.h"
 #include "cc/surfaces/surface_id.h"
 #include "cc/surfaces/surface_sequence.h"
+#include "ui/gfx/size.h"
 
 namespace cc {
 
@@ -29,12 +30,16 @@ class CC_EXPORT SurfaceLayer : public Layer {
       const SatisfyCallback& satisfy_callback,
       const RequireCallback& require_callback);
 
-  void SetSurfaceId(SurfaceId surface_id);
+  void SetSurfaceId(SurfaceId surface_id, const gfx::Size& size);
 
   // Layer overrides.
   scoped_ptr<LayerImpl> CreateLayerImpl(LayerTreeImpl* tree_impl) override;
   void SetLayerTreeHost(LayerTreeHost* host) override;
   void PushPropertiesTo(LayerImpl* layer) override;
+  void CalculateContentsScale(float ideal_contents_scale,
+                              float* contents_scale_x,
+                              float* contents_scale_y,
+                              gfx::Size* content_bounds) override;
 
  protected:
   SurfaceLayer(const SatisfyCallback& satisfy_callback,
@@ -47,6 +52,7 @@ class CC_EXPORT SurfaceLayer : public Layer {
   void SatisfyDestroySequence();
 
   SurfaceId surface_id_;
+  gfx::Size surface_size_;
   SurfaceSequence destroy_sequence_;
   SatisfyCallback satisfy_callback_;
   RequireCallback require_callback_;
diff --git a/cc/layers/surface_layer_unittest.cc b/cc/layers/surface_layer_unittest.cc
index 99d0e17..7323bf4 100644
--- a/cc/layers/surface_layer_unittest.cc
+++ b/cc/layers/surface_layer_unittest.cc
@@ -65,7 +65,7 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   scoped_refptr<SurfaceLayer> layer(SurfaceLayer::Create(
       base::Bind(&SatisfyCallback, &blank_change),
       base::Bind(&RequireCallback, &required_id, &required_seq)));
-  layer->SetSurfaceId(SurfaceId(1));
+  layer->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
   layer_tree_host_->set_surface_id_namespace(1);
   layer_tree_host_->SetRootLayer(layer);
 
@@ -74,7 +74,7 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   scoped_refptr<SurfaceLayer> layer2(SurfaceLayer::Create(
       base::Bind(&SatisfyCallback, &blank_change),
       base::Bind(&RequireCallback, &required_id, &required_seq)));
-  layer2->SetSurfaceId(SurfaceId(1));
+  layer2->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
   layer_tree_host2->set_surface_id_namespace(2);
   layer_tree_host2->SetRootLayer(layer2);
 
@@ -110,6 +110,33 @@ TEST_F(SurfaceLayerTest, MultipleFramesOneSurface) {
   EXPECT_EQ(2u, required_seq.size());
 }
 
+// Check that setting content scale on the surface works.
+TEST_F(SurfaceLayerTest, ScaleSurface) {
+  SurfaceSequence blank_change;
+  SurfaceId required_id;
+  std::set<SurfaceSequence> required_seq;
+  scoped_refptr<SurfaceLayer> layer(SurfaceLayer::Create(
+      base::Bind(&SatisfyCallback, &blank_change),
+      base::Bind(&RequireCallback, &required_id, &required_seq)));
+  gfx::Size surface_size(10, 15);
+  layer->SetSurfaceId(SurfaceId(1), surface_size);
+  layer->SetBounds(gfx::Size(25, 45));
+
+  float scale_x;
+  float scale_y;
+  gfx::Size bounds;
+  layer->CalculateContentsScale(2.f, &scale_x, &scale_y, &bounds);
+  EXPECT_EQ(10.f / 25.f, scale_x);
+  EXPECT_EQ(15.f / 45.f, scale_y);
+  EXPECT_EQ(surface_size.ToString(), bounds.ToString());
+
+  layer->SetBounds(gfx::Size(0, 0));
+  layer->CalculateContentsScale(2.f, &scale_x, &scale_y, &bounds);
+  EXPECT_EQ(1.f, scale_x);
+  EXPECT_EQ(1.f, scale_y);
+  EXPECT_EQ(surface_size.ToString(), bounds.ToString());
+}
+
 // Check that SurfaceSequence is sent through swap promise.
 class SurfaceLayerSwapPromise : public LayerTreeTest {
  public:
@@ -121,7 +148,7 @@ class SurfaceLayerSwapPromise : public LayerTreeTest {
     layer_ = SurfaceLayer::Create(
         base::Bind(&SatisfyCallback, &satisfied_sequence_),
         base::Bind(&RequireCallback, &required_id_, &required_set_));
-    layer_->SetSurfaceId(SurfaceId(1));
+    layer_->SetSurfaceId(SurfaceId(1), gfx::Size(1, 1));
 
     // Layer hasn't been added to tree so no SurfaceSequence generated yet.
     EXPECT_EQ(0u, required_set_.size());