Fix zoom in CSS paint worklets

third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp

Index: third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
diff --git a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
index 7da77ddd4e7984fc8c4db12c8f2b3bfb11788796..4c5fd43241a0457ea988c8699645e58340c18ecc 100644
--- a/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
+++ b/third_party/WebKit/Source/modules/csspaint/CSSPaintDefinition.cpp
@@ -21,6 +21,17 @@
 
 namespace blink {
 
+namespace {
+
+IntSize adjustSizeForZoom(const IntSize& size, float zoom)
+{
+    IntSize newSize(size);
+    newSize.scale(1 / zoom);
+    return newSize;
+}
+
+} // namespace
+
 CSSPaintDefinition* CSSPaintDefinition::create(ScriptState* scriptState, v8::Local<v8::Function> constructor, v8::Local<v8::Function> paint, Vector<CSSPropertyID>& nativeInvalidationProperties, Vector<AtomicString>& customInvalidationProperties)
 {
     return new CSSPaintDefinition(scriptState, constructor, paint, nativeInvalidationProperties, customInvalidationProperties);
@@ -39,8 +50,10 @@ CSSPaintDefinition::~CSSPaintDefinition()
 {
 }
 
-PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject, const IntSize& size)
+PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject, const IntSize& size, float zoom)
 {
+    const auto adjustedSize = adjustSizeForZoom(size, zoom);

[ikilpatrick, 2016/06/30 17:24:54]

add a comment as to why we are doing this.

[Gleb Lanbin, 2016/06/30 23:57:20]

renamed the function and variable to make clear our intention here.

+
     ScriptState::Scope scope(m_scriptState.get());
 
     maybeCreatePaintInstance();
@@ -56,8 +69,8 @@ PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject, co
     DCHECK(layoutObject.node());
 
     PaintRenderingContext2D* renderingContext = PaintRenderingContext2D::create(
-        ImageBuffer::create(wrapUnique(new RecordingImageBufferSurface(size))));
-    PaintSize* paintSize = PaintSize::create(size);
+        ImageBuffer::create(wrapUnique(new RecordingImageBufferSurface(size))), zoom);
+    PaintSize* paintSize = PaintSize::create(adjustedSize);
     StylePropertyMap* styleMap = FilteredComputedStylePropertyMap::create(
         CSSComputedStyleDeclaration::create(layoutObject.node()),
         m_nativeInvalidationProperties, m_customInvalidationProperties);
@@ -81,7 +94,7 @@ PassRefPtr<Image> CSSPaintDefinition::paint(const LayoutObject& layoutObject, co
         return nullptr;
     }
 
-    return PaintGeneratedImage::create(renderingContext->imageBuffer()->getPicture(), size);
+    return PaintGeneratedImage::create(renderingContext->imageBuffer()->getPicture(), adjustedSize);
 }
 
 void CSSPaintDefinition::maybeCreatePaintInstance()