Implement HiDPI and pinch-zoom scaling of filter params

cc/trees/layer_tree_host_pixeltest_filters.cc

Index: cc/trees/layer_tree_host_pixeltest_filters.cc
diff --git a/cc/trees/layer_tree_host_pixeltest_filters.cc b/cc/trees/layer_tree_host_pixeltest_filters.cc
index c8c8c7adf3f5f72bc0f3305f9a312cd25076f430..5303ed1afb9d7b39839e4d1ea6f9d46b2e4cad4b 100644
--- a/cc/trees/layer_tree_host_pixeltest_filters.cc
+++ b/cc/trees/layer_tree_host_pixeltest_filters.cc
@@ -157,6 +157,80 @@ TEST_F(LayerTreeHostFiltersPixelTest, BackgroundFilterBlurOffAxis) {
                    "background_filter_blur_off_axis.png")));
 }
 
+class LayerTreeHostFiltersScaledPixelTest
+    : public LayerTreeHostFiltersPixelTest {
+  virtual void InitializeSettings(LayerTreeSettings* settings) OVERRIDE {
+    // Required so that device scale is inherited by content scale.
+    settings->layer_transforms_should_scale_layer_contents = true;
+  }
+
+  virtual void SetupTree() OVERRIDE {
+    layer_tree_host()->SetDeviceScaleFactor(device_scale_factor_);
+    LayerTreePixelTest::SetupTree();
+  }
+
+ protected:
+  void RunPixelTestType(int content_size,
+                        float device_scale_factor,
+                        PixelTestType test_type) {
+    int half_content = content_size / 2;
+
+    scoped_refptr<SolidColorLayer> root = CreateSolidColorLayer(
+        gfx::Rect(0, 0, content_size, content_size), SK_ColorWHITE);
+
+    scoped_refptr<SolidColorLayer> background = CreateSolidColorLayer(
+        gfx::Rect(0, 0, content_size, content_size), SK_ColorGREEN);
+    root->AddChild(background);
+
+    // Add a blue layer that completely covers the green layer.
+    scoped_refptr<SolidColorLayer> foreground = CreateSolidColorLayer(
+        gfx::Rect(0, 0, content_size, content_size), SK_ColorBLUE);
+    background->AddChild(foreground);
+
+    // Add an alpha threshold filter to the blue layer which will filter out
+    // everything except the lower right corner.
+    FilterOperations filters;
+    SkRegion alpha_region;
+    alpha_region.setRect(
+        half_content, half_content, content_size, content_size);
+    filters.Append(
+        FilterOperation::CreateAlphaThresholdFilter(alpha_region, 1.f, 0.f));
+    foreground->SetFilters(filters);
+
+    device_scale_factor_ = device_scale_factor;
+    RunPixelTest(
+        test_type,
+        background,
+        base::FilePath(FILE_PATH_LITERAL("green_small_with_blue_corner.png")));
+  }
+
+  float device_scale_factor_;
+};
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, StandardDpi_GLBitmap) {
+  RunPixelTestType(100, 1.f, GL_WITH_BITMAP);
+}
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, StandardDpi_GLDefault) {
+  RunPixelTestType(100, 1.f, GL_WITH_DEFAULT);
+}
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, StandardDpi_Software) {
+  RunPixelTestType(100, 1.f, SOFTWARE_WITH_BITMAP);
+}
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, HiDpi_GLBitmap) {
+  RunPixelTestType(50, 2.f, GL_WITH_BITMAP);
+}
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, HiDpi_GLDefault) {
+  RunPixelTestType(50, 2.f, GL_WITH_DEFAULT);
+}
+
+TEST_F(LayerTreeHostFiltersScaledPixelTest, HiDpi_Software) {
+  RunPixelTestType(50, 2.f, SOFTWARE_WITH_BITMAP);
+}
+
 class ImageFilterClippedPixelTest : public LayerTreeHostFiltersPixelTest {
  protected:
   void RunPixelTestType(PixelTestType test_type) {