Make stream captures work on canvases that are not in the DOM.

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

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 49 matching lines @@
 class HitTestCanvasResult;
 class Path2D;
 class TextMetrics;
 
 typedef CSSImageValueOrHTMLImageElementOrHTMLVideoElementOrHTMLCanvasElementOrImageBitmapOrOffscreenCanvas
     CanvasImageSourceUnion;
 
 class MODULES_EXPORT CanvasRenderingContext2D final
     : public CanvasRenderingContext,
       public BaseRenderingContext2D,
-      public WebThread::TaskObserver,
       public SVGResourceClient {
   DEFINE_WRAPPERTYPEINFO();
   USING_GARBAGE_COLLECTED_MIXIN(CanvasRenderingContext2D);
-  USING_PRE_FINALIZER(CanvasRenderingContext2D, dispose);
 
  public:
   class Factory : public CanvasRenderingContextFactory {
     WTF_MAKE_NONCOPYABLE(Factory);
 
    public:
     Factory() {}
     ~Factory() override {}
 
     CanvasRenderingContext* create(HTMLCanvasElement* canvas,
@@ skipping 50 matching lines @@
   void clearHitRegions();
   HitRegion* hitRegionAtPoint(const FloatPoint&);
   unsigned hitRegionsCount() const override;
 
   void loseContext(LostContextMode) override;
   void didSetSurfaceSize() override;
 
   void restoreCanvasMatrixClipStack(PaintCanvas*) const override;
 
   // TaskObserver implementation
-  void didProcessTask() override;
-  void willProcessTask() override {}
+  void didProcessTask() final;
 
   void styleDidChange(const ComputedStyle* oldStyle,
                       const ComputedStyle& newStyle) override;
   HitTestCanvasResult* getControlAndIdIfHitRegionExists(
       const LayoutPoint& location) override;
   String getIdFromControl(const Element*) override;
 
   // SVGResourceClient implementation
   TreeScope* treeScope() override;
   void resourceContentChanged() override;
@@ skipping 15 matching lines @@
   bool hasImageBuffer() const final;
   ImageBuffer* imageBuffer() const final;
 
   bool parseColorOrCurrentColor(Color&, const String& colorString) const final;
 
   PaintCanvas* drawingCanvas() const final;
   PaintCanvas* existingDrawingCanvas() const final;
   void disableDeferral(DisableDeferralReason) final;
 
   AffineTransform baseTransform() const final;
-  void didDraw(const SkIRect& dirtyRect) final;
+  void didDraw(const SkIRect& dirtyRect) final;  // overrides
+                                                 // BaseRenderingContext2D and
+                                                 // CanvasRenderingContext
 
   bool stateHasFilter() final;
   sk_sp<SkImageFilter> stateGetFilter() final;
   void snapshotStateForFilter() final;
 
   void validateStateStack() const final;
 
   PassRefPtr<Image> getImage(AccelerationHint, SnapshotReason) const final;
 
   bool isAccelerationOptimalForCanvasContent() const;
 
   void resetUsageTracking();
 
   void incrementFrameCount() { m_usageCounters.numFramesSinceReset++; }
 
   bool isPaintable() const final { return hasImageBuffer(); }
 
   ColorBehavior drawImageColorBehavior() const final;
 
   void willDrawImage(CanvasImageSource*) const final;
 
  private:
   friend class CanvasRenderingContext2DAutoRestoreSkCanvas;
 
   CanvasRenderingContext2D(HTMLCanvasElement*,
                            const CanvasContextCreationAttributes& attrs,
                            Document&);
 
-  void dispose();
-
   void dispatchContextLostEvent(TimerBase*);
   void dispatchContextRestoredEvent(TimerBase*);
   void tryRestoreContextEvent(TimerBase*);
 
   void pruneLocalFontCache(size_t targetSize);
-  void schedulePruneLocalFontCacheIfNeeded();
 
   void scrollPathIntoViewInternal(const Path&);
 
   void drawTextInternal(const String&,
                         double x,
                         double y,
                         CanvasRenderingContext2DState::PaintType,
                         double* maxWidth = nullptr);
 
   const Font& accessFont();
@@ skipping 21 matching lines @@
   Member<HitRegionManager> m_hitRegionManager;
   LostContextMode m_contextLostMode;
   bool m_contextRestorable;
   unsigned m_tryRestoreContextAttemptCount;
   TaskRunnerTimer<CanvasRenderingContext2D> m_dispatchContextLostEventTimer;
   TaskRunnerTimer<CanvasRenderingContext2D> m_dispatchContextRestoredEventTimer;
   TaskRunnerTimer<CanvasRenderingContext2D> m_tryRestoreContextEventTimer;
 
   FilterOperations m_filterOperations;
   HashMap<String, Font> m_fontsResolvedUsingCurrentStyle;
-  bool m_pruneLocalFontCacheScheduled;
+  bool m_shouldPruneLocalFontCache;
   ListHashSet<String> m_fontLRUList;
 };
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D,
                   CanvasRenderingContext,
                   context,
                   context->is2d() && context->canvas(),
                   context.is2d() && context.canvas());
 
 }  // namespace blink
 
 #endif  // CanvasRenderingContext2D_h