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diff --git a/dom/canvas/DrawTargetWebgl.h b/dom/canvas/DrawTargetWebgl.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef _MOZILLA_GFX_DRAWTARGETWEBGL_H
+#define _MOZILLA_GFX_DRAWTARGETWEBGL_H
+
+#include "mozilla/gfx/2D.h"
+#include "mozilla/gfx/PathSkia.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/WeakPtr.h"
+#include "mozilla/ThreadLocal.h"
+#include "mozilla/ipc/Shmem.h"
+#include <vector>
+
+namespace WGR {
+struct OutputVertex;
+}
+
+namespace mozilla {
+
+class ClientWebGLContext;
+class WebGLBufferJS;
+class WebGLFramebufferJS;
+class WebGLProgramJS;
+class WebGLRenderbufferJS;
+class WebGLTextureJS;
+class WebGLUniformLocationJS;
+class WebGLVertexArrayJS;
+
+namespace layers {
+class SurfaceDescriptor;
+}
+
+namespace gfx {
+
+class DataSourceSurface;
+class DrawTargetSkia;
+class DrawTargetWebgl;
+class PathSkia;
+class SourceSurfaceSkia;
+class SourceSurfaceWebgl;
+
+class TextureHandle;
+class SharedTexture;
+class SharedTextureHandle;
+class StandaloneTexture;
+class GlyphCache;
+class PathCache;
+struct PathVertexRange;
+
+// DrawTargetWebgl implements a subset of the DrawTarget API suitable for use
+// by CanvasRenderingContext2D. It maps these to a client WebGL context so that
+// they can be accelerated where possible by WebGL. It manages both routing to
+// appropriate shaders and texture allocation/caching for surfaces. For commands
+// that are not feasible to accelerate with WebGL, it mirrors state to a backup
+// DrawTargetSkia that can be used as a fallback software renderer. Multiple
+// instances of DrawTargetWebgl within a process will actually share a single
+// WebGL context so that data can be more easily interchanged between them and
+// also to enable more reasonable limiting of resource usage.
+class DrawTargetWebgl : public DrawTarget, public SupportsWeakPtr {
+  friend class SharedTextureHandle;
+  friend class StandaloneTexture;
+  friend class TextureHandle;
+  friend class SourceSurfaceWebgl;
+  friend class AutoSaveContext;
+
+ public:
+  MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DrawTargetWebgl, override)
+
+ private:
+  IntSize mSize;
+  RefPtr<WebGLFramebufferJS> mFramebuffer;
+  RefPtr<WebGLTextureJS> mTex;
+  RefPtr<WebGLTextureJS> mClipMask;
+  // The integer-aligned, scissor-compatible conservative bounds of the clip.
+  IntRect mClipBounds;
+  // The fractional, AA'd bounds of the clip rect, if applicable.
+  Rect mClipAARect;
+  RefPtr<DrawTargetSkia> mSkia;
+  // Skia DT pointing to the same pixel data, but without any applied clips.
+  RefPtr<DrawTargetSkia> mSkiaNoClip;
+  // The Shmem backing the Skia DT, if applicable.
+  mozilla::ipc::Shmem mShmem;
+  // The currently cached snapshot of the WebGL context
+  RefPtr<DataSourceSurface> mSnapshot;
+  // Whether the framebuffer is still in the initially clear state.
+  bool mIsClear = true;
+  // Whether or not the Skia target has valid contents and is being drawn to
+  bool mSkiaValid = false;
+  // Whether or not Skia layering over the WebGL context is enabled
+  bool mSkiaLayer = false;
+  // Whether the WebGL target was clear when the Skia layer was established.
+  bool mSkiaLayerClear = false;
+  // Whether or not the WebGL context has valid contents and is being drawn to
+  bool mWebglValid = true;
+  // Whether or not the clip state has changed since last used by SharedContext.
+  bool mClipChanged = true;
+  // Whether or not the clip state needs to be refreshed. Sometimes the clip
+  // state may be overwritten and require a refresh later, even though it has
+  // not changed.
+  bool mRefreshClipState = true;
+  // The framebuffer has been modified and should be copied to the swap chain.
+  bool mNeedsPresent = true;
+  // The number of layers currently pushed.
+  int32_t mLayerDepth = 0;
+
+  RefPtr<TextureHandle> mSnapshotTexture;
+
+  // Store a log of clips currently pushed so that they can be used to init
+  // the clip state of temporary DTs.
+  struct ClipStack {
+    Matrix mTransform;
+    Rect mRect;
+    RefPtr<const Path> mPath;
+
+    bool operator==(const ClipStack& aOther) const;
+  };
+
+  std::vector<ClipStack> mClipStack;
+
+  // The previous state of the clip stack when a mask was generated.
+  std::vector<ClipStack> mCachedClipStack;
+
+  // UsageProfile stores per-frame counters for significant profiling events
+  // that assist in determining whether acceleration should still be used for
+  // a Canvas2D user.
+  struct UsageProfile {
+    uint32_t mFailedFrames = 0;
+    uint32_t mFrameCount = 0;
+    uint32_t mCacheMisses = 0;
+    uint32_t mCacheHits = 0;
+    uint32_t mUncachedDraws = 0;
+    uint32_t mLayers = 0;
+    uint32_t mReadbacks = 0;
+    uint32_t mFallbacks = 0;
+
+    void BeginFrame();
+    void EndFrame();
+    bool RequiresRefresh() const;
+
+    void OnCacheMiss() { ++mCacheMisses; }
+    void OnCacheHit() { ++mCacheHits; }
+    void OnUncachedDraw() { ++mUncachedDraws; }
+    void OnLayer() { ++mLayers; }
+    void OnReadback() { ++mReadbacks; }
+    void OnFallback() { ++mFallbacks; }
+  };
+
+  UsageProfile mProfile;
+
+  // SharedContext stores most of the actual WebGL state that may be used by
+  // any number of DrawTargetWebgl's that use it. Foremost, it holds the actual
+  // WebGL client context, programs, and buffers for mapping to WebGL.
+  // Secondarily, it holds shared caches for surfaces, glyphs, paths, and
+  // shadows so that each DrawTargetWebgl does not require its own cache. It is
+  // important that SetTarget is called to install the current DrawTargetWebgl
+  // before actually using the SharedContext, as the individual framebuffers
+  // and viewport are still maintained in DrawTargetWebgl itself.
+  class SharedContext : public mozilla::RefCounted<SharedContext>,
+                        public mozilla::SupportsWeakPtr {
+   public:
+    MOZ_DECLARE_REFCOUNTED_TYPENAME(SharedContext)
+
+    SharedContext();
+    ~SharedContext();
+
+    WeakPtr<DrawTargetWebgl> mCurrentTarget;
+    IntSize mViewportSize;
+    // The current integer-aligned scissor rect.
+    IntRect mClipRect;
+    // The current fractional AA'd clip rect bounds.
+    Rect mClipAARect;
+
+    RefPtr<ClientWebGLContext> mWebgl;
+
+    // Avoid spurious state changes by caching last used state.
+    RefPtr<WebGLProgramJS> mLastProgram;
+    RefPtr<WebGLTextureJS> mLastTexture;
+    RefPtr<WebGLTextureJS> mLastClipMask;
+    // Whether the shader viewport state requires updating.
+    bool mDirtyViewport = true;
+    // Whether the shader anti-aliasing state requires updating.
+    bool mDirtyAA = true;
+    // Whether the shader clip AA bounds require updating.
+    bool mDirtyClip = true;
+
+    // WebGL shader resources
+    RefPtr<WebGLBufferJS> mPathVertexBuffer;
+    RefPtr<WebGLVertexArrayJS> mPathVertexArray;
+    // The current insertion offset into the GPU path buffer.
+    uint32_t mPathVertexOffset = 0;
+    // The maximum size of the GPU path buffer.
+    uint32_t mPathVertexCapacity = 0;
+    // The maximum supported type complexity of a GPU path.
+    uint32_t mPathMaxComplexity = 0;
+    // Whether to accelerate stroked paths with AAStroke.
+    bool mPathAAStroke = true;
+    // Whether to accelerate stroked paths with WGR.
+    bool mPathWGRStroke = false;
+    // Temporary buffer for generating WGR output into.
+    UniquePtr<WGR::OutputVertex[]> mWGROutputBuffer;
+    RefPtr<WebGLProgramJS> mSolidProgram;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramViewport;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramAA;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramTransform;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramColor;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramClipMask;
+    RefPtr<WebGLUniformLocationJS> mSolidProgramClipBounds;
+    RefPtr<WebGLProgramJS> mImageProgram;
+    RefPtr<WebGLUniformLocationJS> mImageProgramViewport;
+    RefPtr<WebGLUniformLocationJS> mImageProgramAA;
+    RefPtr<WebGLUniformLocationJS> mImageProgramTransform;
+    RefPtr<WebGLUniformLocationJS> mImageProgramTexMatrix;
+    RefPtr<WebGLUniformLocationJS> mImageProgramTexBounds;
+    RefPtr<WebGLUniformLocationJS> mImageProgramColor;
+    RefPtr<WebGLUniformLocationJS> mImageProgramSwizzle;
+    RefPtr<WebGLUniformLocationJS> mImageProgramSampler;
+    RefPtr<WebGLUniformLocationJS> mImageProgramClipMask;
+    RefPtr<WebGLUniformLocationJS> mImageProgramClipBounds;
+
+    // Scratch framebuffer used to wrap textures for miscellaneous utility ops.
+    RefPtr<WebGLFramebufferJS> mScratchFramebuffer;
+    // Buffer filled with zero data for initializing textures.
+    RefPtr<WebGLBufferJS> mZeroBuffer;
+    size_t mZeroSize = 0;
+    // 1x1 texture with solid white mask for disabling clipping
+    RefPtr<WebGLTextureJS> mNoClipMask;
+
+    uint32_t mMaxTextureSize = 0;
+    bool mRasterizationTruncates = false;
+
+    // The current blending operation.
+    CompositionOp mLastCompositionOp = CompositionOp::OP_SOURCE;
+    // The constant blend color used for the blending operation.
+    Maybe<DeviceColor> mLastBlendColor;
+
+    // The cached scissor state. Operations that rely on scissor state should
+    // take care to enable or disable the cached scissor state as necessary.
+    bool mScissorEnabled = false;
+    IntRect mLastScissor = {-1, -1, -1, -1};
+
+    // A most-recently-used list of allocated texture handles.
+    LinkedList<RefPtr<TextureHandle>> mTextureHandles;
+    size_t mNumTextureHandles = 0;
+    // User data key linking a SourceSurface with its TextureHandle.
+    UserDataKey mTextureHandleKey = {0};
+    // User data key linking a SourceSurface with its shadow blur TextureHandle.
+    UserDataKey mShadowTextureKey = {0};
+    // User data key linking a ScaledFont with its GlyphCache.
+    UserDataKey mGlyphCacheKey = {0};
+    // List of all GlyphCaches currently allocated to fonts.
+    LinkedList<GlyphCache> mGlyphCaches;
+    // Cache of rasterized paths.
+    UniquePtr<PathCache> mPathCache;
+    // Collection of allocated shared texture pages that may be shared amongst
+    // many handles.
+    std::vector<RefPtr<SharedTexture>> mSharedTextures;
+    // Collection of allocated standalone textures that have a single assigned
+    // handle.
+    std::vector<RefPtr<StandaloneTexture>> mStandaloneTextures;
+    size_t mUsedTextureMemory = 0;
+    size_t mTotalTextureMemory = 0;
+    // The total reserved memory for empty texture pages that are kept around
+    // for future allocations.
+    size_t mEmptyTextureMemory = 0;
+    // A memory pressure event may signal from another thread that caches should
+    // be cleared if possible.
+    Atomic<bool> mShouldClearCaches;
+    // Whether the Shmem is currently being processed by the remote side. If so,
+    // we need to wait for processing to complete before any further commands
+    // modifying the Skia DT can proceed.
+    bool mWaitForShmem = false;
+
+    const Matrix& GetTransform() const { return mCurrentTarget->mTransform; }
+
+    bool IsContextLost() const;
+
+    bool Initialize();
+    bool CreateShaders();
+    void ResetPathVertexBuffer(bool aChanged = true);
+
+    void SetBlendState(CompositionOp aOp,
+                       const Maybe<DeviceColor>& aBlendColor = Nothing());
+
+    void SetClipRect(const Rect& aClipRect);
+    void SetClipRect(const IntRect& aClipRect) { SetClipRect(Rect(aClipRect)); }
+    bool SetClipMask(const RefPtr<WebGLTextureJS>& aTex);
+    bool SetNoClipMask();
+    bool HasClipMask() const {
+      return mLastClipMask && mLastClipMask != mNoClipMask;
+    }
+
+    bool IsCurrentTarget(DrawTargetWebgl* aDT) const {
+      return aDT == mCurrentTarget;
+    }
+    bool SetTarget(DrawTargetWebgl* aDT);
+
+    // Reset the current target.
+    void ClearTarget() { mCurrentTarget = nullptr; }
+    // Reset the last used texture to force binding next use.
+    void ClearLastTexture();
+
+    bool SupportsPattern(const Pattern& aPattern);
+
+    void EnableScissor(const IntRect& aRect);
+    void DisableScissor();
+
+    void SetTexFilter(WebGLTextureJS* aTex, bool aFilter);
+    void InitTexParameters(WebGLTextureJS* aTex, bool aFilter = true);
+
+    bool ReadInto(uint8_t* aDstData, int32_t aDstStride, SurfaceFormat aFormat,
+                  const IntRect& aBounds, TextureHandle* aHandle = nullptr);
+    already_AddRefed<DataSourceSurface> ReadSnapshot(
+        TextureHandle* aHandle = nullptr);
+    already_AddRefed<TextureHandle> WrapSnapshot(const IntSize& aSize,
+                                                 SurfaceFormat aFormat,
+                                                 RefPtr<WebGLTextureJS> aTex);
+    already_AddRefed<TextureHandle> CopySnapshot(
+        const IntRect& aRect, TextureHandle* aHandle = nullptr);
+
+    already_AddRefed<WebGLTextureJS> GetCompatibleSnapshot(
+        SourceSurface* aSurface) const;
+    bool IsCompatibleSurface(SourceSurface* aSurface) const;
+
+    bool UploadSurface(DataSourceSurface* aData, SurfaceFormat aFormat,
+                       const IntRect& aSrcRect, const IntPoint& aDstOffset,
+                       bool aInit, bool aZero = false,
+                       const RefPtr<WebGLTextureJS>& aTex = nullptr);
+    bool DrawRectAccel(const Rect& aRect, const Pattern& aPattern,
+                       const DrawOptions& aOptions,
+                       Maybe<DeviceColor> aMaskColor = Nothing(),
+                       RefPtr<TextureHandle>* aHandle = nullptr,
+                       bool aTransformed = true, bool aClipped = true,
+                       bool aAccelOnly = false, bool aForceUpdate = false,
+                       const StrokeOptions* aStrokeOptions = nullptr,
+                       const PathVertexRange* aVertexRange = nullptr);
+
+    bool DrawPathAccel(const Path* aPath, const Pattern& aPattern,
+                       const DrawOptions& aOptions,
+                       const StrokeOptions* aStrokeOptions = nullptr,
+                       const ShadowOptions* aShadow = nullptr,
+                       bool aCacheable = true);
+
+    bool DrawGlyphsAccel(ScaledFont* aFont, const GlyphBuffer& aBuffer,
+                         const Pattern& aPattern, const DrawOptions& aOptions,
+                         const StrokeOptions* aStrokeOptions,
+                         bool aUseSubpixelAA);
+
+    void PruneTextureHandle(const RefPtr<TextureHandle>& aHandle);
+    bool PruneTextureMemory(size_t aMargin = 0, bool aPruneUnused = true);
+
+    bool RemoveSharedTexture(const RefPtr<SharedTexture>& aTexture);
+    bool RemoveStandaloneTexture(const RefPtr<StandaloneTexture>& aTexture);
+
+    void UnlinkSurfaceTextures();
+    void UnlinkSurfaceTexture(const RefPtr<TextureHandle>& aHandle);
+    void UnlinkGlyphCaches();
+
+    void OnMemoryPressure();
+    void ClearAllTextures();
+    void ClearEmptyTextureMemory();
+    void ClearCachesIfNecessary();
+
+    void WaitForShmem(DrawTargetWebgl* aTarget);
+
+    void CachePrefs();
+  };
+
+  RefPtr<SharedContext> mSharedContext;
+
+  static MOZ_THREAD_LOCAL(SharedContext*) sSharedContext;
+
+  // Try to keep around the shared context for the main thread in case canvases
+  // are rapidly recreated and destroyed.
+  static RefPtr<SharedContext> sMainSharedContext;
+
+ public:
+  DrawTargetWebgl();
+  ~DrawTargetWebgl();
+
+  static already_AddRefed<DrawTargetWebgl> Create(const IntSize& aSize,
+                                                  SurfaceFormat aFormat);
+
+  bool Init(const IntSize& aSize, SurfaceFormat aFormat);
+
+  bool IsValid() const override;
+
+  DrawTargetType GetType() const override {
+    return DrawTargetType::HARDWARE_RASTER;
+  }
+  BackendType GetBackendType() const override { return BackendType::WEBGL; }
+  IntSize GetSize() const override { return mSize; }
+
+  already_AddRefed<SourceSurface> GetDataSnapshot();
+  already_AddRefed<SourceSurface> Snapshot() override;
+  already_AddRefed<SourceSurface> GetOptimizedSnapshot(DrawTarget* aTarget);
+  already_AddRefed<SourceSurface> GetBackingSurface() override;
+  void DetachAllSnapshots() override;
+
+  void BeginFrame(const IntRect& aPersistedRect);
+  void EndFrame();
+  bool RequiresRefresh() const { return mProfile.RequiresRefresh(); }
+
+  bool LockBits(uint8_t** aData, IntSize* aSize, int32_t* aStride,
+                SurfaceFormat* aFormat, IntPoint* aOrigin = nullptr) override;
+  void ReleaseBits(uint8_t* aData) override;
+
+  void Flush() override {}
+  void DrawSurface(
+      SourceSurface* aSurface, const Rect& aDest, const Rect& aSource,
+      const DrawSurfaceOptions& aSurfOptions = DrawSurfaceOptions(),
+      const DrawOptions& aOptions = DrawOptions()) override;
+  void DrawFilter(FilterNode* aNode, const Rect& aSourceRect,
+                  const Point& aDestPoint,
+                  const DrawOptions& aOptions = DrawOptions()) override;
+  void DrawSurfaceWithShadow(SourceSurface* aSurface, const Point& aDest,
+                             const ShadowOptions& aShadow,
+                             CompositionOp aOperator) override;
+  void DrawShadow(const Path* aPath, const Pattern& aPattern,
+                  const ShadowOptions& aShadow, const DrawOptions& aOptions,
+                  const StrokeOptions* aStrokeOptions = nullptr) override;
+
+  void ClearRect(const Rect& aRect) override;
+  void CopySurface(SourceSurface* aSurface, const IntRect& aSourceRect,
+                   const IntPoint& aDestination) override;
+  void FillRect(const Rect& aRect, const Pattern& aPattern,
+                const DrawOptions& aOptions = DrawOptions()) override;
+  void StrokeRect(const Rect& aRect, const Pattern& aPattern,
+                  const StrokeOptions& aStrokeOptions = StrokeOptions(),
+                  const DrawOptions& aOptions = DrawOptions()) override;
+  bool StrokeLineAccel(const Point& aStart, const Point& aEnd,
+                       const Pattern& aPattern,
+                       const StrokeOptions& aStrokeOptions,
+                       const DrawOptions& aOptions, bool aClosed = false);
+  void StrokeLine(const Point& aStart, const Point& aEnd,
+                  const Pattern& aPattern,
+                  const StrokeOptions& aStrokeOptions = StrokeOptions(),
+                  const DrawOptions& aOptions = DrawOptions()) override;
+  void Stroke(const Path* aPath, const Pattern& aPattern,
+              const StrokeOptions& aStrokeOptions = StrokeOptions(),
+              const DrawOptions& aOptions = DrawOptions()) override;
+  void Fill(const Path* aPath, const Pattern& aPattern,
+            const DrawOptions& aOptions = DrawOptions()) override;
+
+  void SetPermitSubpixelAA(bool aPermitSubpixelAA) override;
+  void FillGlyphs(ScaledFont* aFont, const GlyphBuffer& aBuffer,
+                  const Pattern& aPattern,
+                  const DrawOptions& aOptions = DrawOptions()) override;
+  void StrokeGlyphs(ScaledFont* aFont, const GlyphBuffer& aBuffer,
+                    const Pattern& aPattern,
+                    const StrokeOptions& aStrokeOptions = StrokeOptions(),
+                    const DrawOptions& aOptions = DrawOptions()) override;
+  void Mask(const Pattern& aSource, const Pattern& aMask,
+            const DrawOptions& aOptions = DrawOptions()) override;
+  void MaskSurface(const Pattern& aSource, SourceSurface* aMask, Point aOffset,
+                   const DrawOptions& aOptions = DrawOptions()) override;
+  bool Draw3DTransformedSurface(SourceSurface* aSurface,
+                                const Matrix4x4& aMatrix) override;
+  void PushClip(const Path* aPath) override;
+  void PushClipRect(const Rect& aRect) override;
+  void PushDeviceSpaceClipRects(const IntRect* aRects,
+                                uint32_t aCount) override;
+  void PopClip() override;
+  bool RemoveAllClips() override;
+  void PushLayer(bool aOpaque, Float aOpacity, SourceSurface* aMask,
+                 const Matrix& aMaskTransform,
+                 const IntRect& aBounds = IntRect(),
+                 bool aCopyBackground = false) override;
+  void PushLayerWithBlend(
+      bool aOpaque, Float aOpacity, SourceSurface* aMask,
+      const Matrix& aMaskTransform, const IntRect& aBounds = IntRect(),
+      bool aCopyBackground = false,
+      CompositionOp aCompositionOp = CompositionOp::OP_OVER) override;
+  void PopLayer() override;
+  already_AddRefed<SourceSurface> CreateSourceSurfaceFromData(
+      unsigned char* aData, const IntSize& aSize, int32_t aStride,
+      SurfaceFormat aFormat) const override;
+  already_AddRefed<SourceSurface> OptimizeSourceSurface(
+      SourceSurface* aSurface) const override;
+  already_AddRefed<SourceSurface> OptimizeSourceSurfaceForUnknownAlpha(
+      SourceSurface* aSurface) const override;
+  already_AddRefed<SourceSurface> CreateSourceSurfaceFromNativeSurface(
+      const NativeSurface& aSurface) const override;
+  already_AddRefed<DrawTarget> CreateSimilarDrawTarget(
+      const IntSize& aSize, SurfaceFormat aFormat) const override;
+  bool CanCreateSimilarDrawTarget(const IntSize& aSize,
+                                  SurfaceFormat aFormat) const override;
+  RefPtr<DrawTarget> CreateClippedDrawTarget(const Rect& aBounds,
+                                             SurfaceFormat aFormat) override;
+
+  already_AddRefed<PathBuilder> CreatePathBuilder(
+      FillRule aFillRule = FillRule::FILL_WINDING) const override;
+  already_AddRefed<GradientStops> CreateGradientStops(
+      GradientStop* aStops, uint32_t aNumStops,
+      ExtendMode aExtendMode = ExtendMode::CLAMP) const override;
+  already_AddRefed<FilterNode> CreateFilter(FilterType aType) override;
+  void SetTransform(const Matrix& aTransform) override;
+  void* GetNativeSurface(NativeSurfaceType aType) override;
+
+  Maybe<layers::SurfaceDescriptor> GetFrontBuffer();
+
+  void OnMemoryPressure() { mSharedContext->OnMemoryPressure(); }
+
+  operator std::string() const {
+    std::stringstream stream;
+    stream << "DrawTargetWebgl(" << this << ")";
+    return stream.str();
+  }
+
+ private:
+  bool SupportsPattern(const Pattern& aPattern) {
+    return mSharedContext->SupportsPattern(aPattern);
+  }
+
+  bool SetSimpleClipRect();
+  bool GenerateComplexClipMask();
+  bool PrepareContext(bool aClipped = true);
+
+  void DrawRectFallback(const Rect& aRect, const Pattern& aPattern,
+                        const DrawOptions& aOptions,
+                        Maybe<DeviceColor> aMaskColor = Nothing(),
+                        bool aTransform = true, bool aClipped = true,
+                        const StrokeOptions* aStrokeOptions = nullptr);
+  bool DrawRect(const Rect& aRect, const Pattern& aPattern,
+                const DrawOptions& aOptions,
+                Maybe<DeviceColor> aMaskColor = Nothing(),
+                RefPtr<TextureHandle>* aHandle = nullptr,
+                bool aTransformed = true, bool aClipped = true,
+                bool aAccelOnly = false, bool aForceUpdate = false,
+                const StrokeOptions* aStrokeOptions = nullptr);
+
+  ColorPattern GetClearPattern() const;
+
+  bool RectContainsViewport(const Rect& aRect) const;
+
+  bool ShouldAccelPath(const DrawOptions& aOptions,
+                       const StrokeOptions* aStrokeOptions);
+  void DrawPath(const Path* aPath, const Pattern& aPattern,
+                const DrawOptions& aOptions,
+                const StrokeOptions* aStrokeOptions = nullptr);
+
+  bool MarkChanged();
+
+  void ReadIntoSkia();
+  void FlattenSkia();
+  bool FlushFromSkia();
+
+  void WaitForShmem() {
+    if (mSharedContext->mWaitForShmem) {
+      mSharedContext->WaitForShmem(this);
+    }
+  }
+
+  void MarkSkiaChanged(bool aOverwrite = false) {
+    WaitForShmem();
+    if (aOverwrite) {
+      mSkiaValid = true;
+      mSkiaLayer = false;
+    } else if (!mSkiaValid) {
+      ReadIntoSkia();
+    } else if (mSkiaLayer) {
+      FlattenSkia();
+    }
+    mWebglValid = false;
+    mIsClear = false;
+  }
+
+  void MarkSkiaChanged(const DrawOptions& aOptions);
+
+  bool ShouldUseSubpixelAA(ScaledFont* aFont, const DrawOptions& aOptions);
+
+  bool ReadInto(uint8_t* aDstData, int32_t aDstStride);
+  already_AddRefed<DataSourceSurface> ReadSnapshot();
+  already_AddRefed<TextureHandle> CopySnapshot(const IntRect& aRect);
+  already_AddRefed<TextureHandle> CopySnapshot() {
+    return CopySnapshot(GetRect());
+  }
+
+  void ClearSnapshot(bool aCopyOnWrite = true, bool aNeedHandle = false);
+
+  bool CreateFramebuffer();
+
+  // PrepareContext may sometimes be used recursively. When this occurs, ensure
+  // that clip state is restored after the context is used.
+  struct AutoRestoreContext {
+    DrawTargetWebgl* mTarget;
+    Rect mClipAARect;
+    RefPtr<WebGLTextureJS> mLastClipMask;
+
+    explicit AutoRestoreContext(DrawTargetWebgl* aTarget);
+
+    ~AutoRestoreContext();
+  };
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif  // _MOZILLA_GFX_DRAWTARGETWEBGL_H