Expose if we are using swiftshader via WebGraphicsContext3DProvider.

third_party/WebKit/Source/platform/graphics/Canvas2DLayerBridge.h

 /*
  * Copyright (C) 2012 Google 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 67 matching lines @@
 
 class PLATFORM_EXPORT Canvas2DLayerBridge : public NON_EXPORTED_BASE(cc::TextureLayerClient), public WebThread::TaskObserver, public RefCounted<Canvas2DLayerBridge> {
     WTF_MAKE_NONCOPYABLE(Canvas2DLayerBridge);
 public:
     enum AccelerationMode {
         DisableAcceleration,
         EnableAcceleration,
         ForceAccelerationForTesting,
     };
 
-    static PassRefPtr<Canvas2DLayerBridge> create(const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
-
+    Canvas2DLayerBridge(std::unique_ptr<WebGraphicsContext3DProvider>, const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
     ~Canvas2DLayerBridge() override;
 
     // cc::TextureLayerClient implementation.
     bool PrepareTextureMailbox(
         cc::TextureMailbox* outMailbox,
         std::unique_ptr<cc::SingleReleaseCallback>* outReleaseCallback,
         bool useSharedMemory) override;
 
     // Callback for mailboxes given to the compositor from PrepareTextureMailbox.
     void mailboxReleased(const gpu::Mailbox&, const gpu::SyncToken&,
@@ skipping 82 matching lines @@
 #if USE_IOSURFACE_FOR_2D_CANVAS
         // If this mailbox wraps an IOSurface-backed texture, the ids of the
         // CHROMIUM image and the texture.
         ImageInfo m_imageInfo;
 #endif // USE_IOSURFACE_FOR_2D_CANVAS
 
         MailboxInfo(const MailboxInfo&);
         MailboxInfo();
     };
 
-    Canvas2DLayerBridge(std::unique_ptr<WebGraphicsContext3DProvider>, const IntSize&, int msaaSampleCount, OpacityMode, AccelerationMode);
     gpu::gles2::GLES2Interface* contextGL();
     void startRecording();
     void skipQueuedDrawCommands();
     void flushRecordingOnly();
     void unregisterTaskObserver();
     void reportSurfaceCreationFailure();
 
     // WebThread::TaskOberver implementation
     void willProcessTask() override;
     void didProcessTask() override;
@@ skipping 80 matching lines @@
     // Each element in this vector represents an IOSurface backed texture that
     // is ready to be reused.
     // Elements in this vector can safely be purged in low memory conditions.
     Vector<ImageInfo> m_imageInfoCache;
 #endif // USE_IOSURFACE_FOR_2D_CANVAS
 };
 
 } // namespace blink
 
 #endif