Reland "webgl: use immutable texture for the default FBO."

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
index a78cbf82e0ff00bf5530292b8155f3006eb8d47b..5d31262e6980df3180890d24afc57cea85f70599 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.h
@@ -131,7 +131,6 @@ class MODULES_EXPORT WebGLRenderingContextBase : public CanvasRenderingContext {
 public:
     ~WebGLRenderingContextBase() override;
 
-    virtual unsigned version() const = 0;
     virtual String contextName() const = 0;
     virtual void registerContextExtensions() = 0;
 
@@ -143,6 +142,8 @@ public:
     static std::unique_ptr<WebGraphicsContext3DProvider> createWebGraphicsContext3DProvider(ScriptState*, WebGLContextAttributes, unsigned webGLVersion);
     static void forceNextWebGLContextCreationToFail();
 
+    unsigned version() const { return m_version; }
+
     int drawingBufferWidth() const;
     int drawingBufferHeight() const;
 
@@ -430,8 +431,8 @@ protected:
     friend class ScopedTexture2DRestorer;
     friend class ScopedFramebufferRestorer;
 
-    WebGLRenderingContextBase(HTMLCanvasElement*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&);
-    WebGLRenderingContextBase(OffscreenCanvas*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&);
+    WebGLRenderingContextBase(HTMLCanvasElement*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&, unsigned);
+    WebGLRenderingContextBase(OffscreenCanvas*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&, unsigned);
     PassRefPtr<DrawingBuffer> createDrawingBuffer(std::unique_ptr<WebGraphicsContext3DProvider>);
     void setupFlags();
 
@@ -1107,10 +1108,12 @@ protected:
     static const char* getTexImageFunctionName(TexImageFunctionID);
 
 private:
-    WebGLRenderingContextBase(HTMLCanvasElement*, OffscreenCanvas*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&);
+    WebGLRenderingContextBase(HTMLCanvasElement*, OffscreenCanvas*, std::unique_ptr<WebGraphicsContext3DProvider>, const WebGLContextAttributes&, unsigned);
     static std::unique_ptr<WebGraphicsContext3DProvider> createContextProviderInternal(HTMLCanvasElement*, ScriptState*, WebGLContextAttributes, unsigned);
     void texImageCanvasByGPU(HTMLCanvasElement*, GLuint, GLenum, GLenum, GLint);
     void texImageBitmapByGPU(ImageBitmap*, GLuint, GLenum, GLenum, GLint, bool);
+
+    const unsigned m_version;
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());