Refactoring source image usage in CanvasRenderingContext2D

Source/core/html/HTMLCanvasElement.cpp

Index: Source/core/html/HTMLCanvasElement.cpp
diff --git a/Source/core/html/HTMLCanvasElement.cpp b/Source/core/html/HTMLCanvasElement.cpp
index 24bd1e3bee912b6a8d843fb1362c0aff6b18c242..b5c40e284604ae206a35076b6341871fdc01b520 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -599,4 +599,38 @@ void HTMLCanvasElement::didMoveToNewDocument(Document& oldDocument)
     HTMLElement::didMoveToNewDocument(oldDocument);
 }
 
+PassRefPtr<Image> HTMLCanvasElement::getSourceImageForCanvas(ExceptionState& exceptionState, CanvasImageSourceUsage usage, bool* isVolatile) const
+{
+    if (isVolatile)
+        *isVolatile = false;
+    if (!width() || !height()) {
+        if (usage == PatternCanvasImageSourceUsage)
+            exceptionState.throwDOMException(InvalidStateError, String::format("The source %s is 0.", width() ? "height" : "width"));
+        return nullptr;
+    }
+
+    if (usage == PatternCanvasImageSourceUsage || usage == DrawToSelfCanvasImageSourceUsage)
+        return copiedImage();
+
+    if (m_context && m_context->is3d()) {
+        m_context->paintRenderingResultsToCanvas();
+        // We leave isVolatile to false when the source is a 2D canvas because
+        // 2d canvas-to-canvas copies are not deferred and all 2D canvases live
+        // in the same graphics context so we can avoid triggering an
+        // unnecessary flush in CanvasRenderingContext2D::drawImage
+        *isVolatile = true;
+    }
+    return buffer() ? m_imageBuffer->copyImage(DontCopyBackingStore, Unscaled) : nullptr;
+}
+
+bool HTMLCanvasElement::wouldTaintOrigin(SecurityOrigin*) const
+{
+    return !originClean();
+}
+
+FloatSize HTMLCanvasElement::sourceSize() const
+{
+    return FloatSize(width(), height());
+}
+
 }