Make OffscreenCanvas a member of CanvasImageSource

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h

Index: third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h
diff --git a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h
index e785a1cd097575441ec33c6a8ce3bcc1dd27e540..acdf4102c3d5ed156fd33b0434c07103df8aa97e 100644
--- a/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h
+++ b/third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h
@@ -60,7 +60,7 @@ class Path2D;
 class SVGMatrixTearOff;
 class TextMetrics;
 
-typedef HTMLImageElementOrHTMLVideoElementOrHTMLCanvasElementOrImageBitmap CanvasImageSourceUnion;
+typedef HTMLImageElementOrHTMLVideoElementOrHTMLCanvasElementOrImageBitmapOrOffscreenCanvas CanvasImageSourceUnion;
 
 class MODULES_EXPORT CanvasRenderingContext2D final : public CanvasRenderingContext, public BaseRenderingContext2D, public WebThread::TaskObserver, public SVGResourceClient {
     DEFINE_WRAPPERTYPEINFO();
@@ -167,11 +167,15 @@ public:
 
     void validateStateStack() final;
 
+    PassRefPtr<Image> getImage(SnapshotReason) const final;
+
     bool isAccelerationOptimalForCanvasContent() const;
 
     void resetUsageTracking();
 
-    void incrementFrameCount() { m_usageCounters.numFramesSinceReset++; };
+    void incrementFrameCount() { m_usageCounters.numFramesSinceReset++; }
+
+    bool isPaintable() const final { return hasImageBuffer(); }
 
 private:
     friend class CanvasRenderingContext2DAutoRestoreSkCanvas;
@@ -225,12 +229,6 @@ private:
     HashMap<String, Font> m_fontsResolvedUsingCurrentStyle;
     bool m_pruneLocalFontCacheScheduled;
     ListHashSet<String> m_fontLRUList;
-
-    bool isPaintable() const final
-    {
-        NOTREACHED();
-        return false;
-    }
 };
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D, CanvasRenderingContext, context,