Fix 2D canvas state persistency after OffscreenCanvas.transferToImageBitmap

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

Index: third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
diff --git a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
index 96c8a22dcdc363acd8d5531af65a3079dbbd880c..3b84e6e22ae42fb8e7f025da09be7b285ecd5d5b 100644
--- a/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
+++ b/third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp
@@ -73,7 +73,11 @@ ImageBuffer* OffscreenCanvasRenderingContext2D::imageBuffer() const
         // TODO: crbug.com/593514 Add support for GPU rendering
         OffscreenCanvasRenderingContext2D* nonConstThis = const_cast<OffscreenCanvasRenderingContext2D*>(this);
         nonConstThis->m_imageBuffer = ImageBuffer::create(IntSize(width(), height()), m_hasAlpha ? NonOpaque : Opaque, InitializeImagePixels);
-        // TODO: crbug.com/593349 Restore matrix and clip state on the new ImageBuffer.
+
+        if (m_needsMatrixClipRestore) {
+            restoreMatrixClipStack(m_imageBuffer->canvas());
+            nonConstThis->m_needsMatrixClipRestore = false;
+        }
     }
 
     return m_imageBuffer.get();
@@ -88,6 +92,7 @@ ImageBitmap* OffscreenCanvasRenderingContext2D::transferToImageBitmap(ExceptionS
     RefPtr<StaticBitmapImage> image = StaticBitmapImage::create(skImage.release());
     image->setOriginClean(this->originClean());
     m_imageBuffer.reset(); // "Transfer" means no retained buffer
+    m_needsMatrixClipRestore = true;
     return ImageBitmap::create(image.release());
 }