Fix content scripts that use WebGL.

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

 /*
  * Copyright (C) 2009 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1395 matching lines @@
 void WebGLRenderingContextBase::attachShader(ScriptState* scriptState, WebGLProgram* program, WebGLShader* shader)
 {
     if (isContextLost() || !validateWebGLObject("attachShader", program) || !validateWebGLObject("attachShader", shader))
         return;
     if (!program->attachShader(shader)) {
         synthesizeGLError(GL_INVALID_OPERATION, "attachShader", "shader attachment already has shader");
         return;
     }
     contextGL()->AttachShader(objectOrZero(program), objectOrZero(shader));
     shader->onAttached();
-    preserveObjectWrapper(scriptState, program, V8HiddenValue::webglShaders(scriptState->isolate()), program->getPersistentCache(), static_cast<uint32_t>(shader->type()), shader);
+    preserveObjectWrapper(scriptState, program, V8PrivateProperty::getWebGLProgramShaders(scriptState->isolate()), static_cast<uint32_t>(shader->type()), shader);
 }
 
 void WebGLRenderingContextBase::bindAttribLocation(WebGLProgram* program, GLuint index, const String& name)
 {
     if (isContextLost() || !validateWebGLObject("bindAttribLocation", program))
         return;
     if (!validateLocationLength("bindAttribLocation", name))
         return;
     if (isPrefixReserved(name)) {
         synthesizeGLError(GL_INVALID_OPERATION, "bindAttribLocation", "reserved prefix");
@@ skipping 58 matching lines @@
     PreservedWrapperIndex idx = PreservedArrayBuffer;
     switch (target) {
     case GL_ARRAY_BUFFER:
         idx = PreservedArrayBuffer;
         break;
     case GL_ELEMENT_ARRAY_BUFFER:
         idx = PreservedElementArrayBuffer;
         break;
     }
 
-    preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, static_cast<uint32_t>(idx), buffer);
+    preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), static_cast<uint32_t>(idx), buffer);
     maybePreserveDefaultVAOObjectWrapper(scriptState);
 }
 
 void WebGLRenderingContextBase::bindFramebuffer(ScriptState* scriptState, GLenum target, WebGLFramebuffer* buffer)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindFramebuffer", buffer, deleted))
         return;
 
     if (deleted)
         buffer = 0;
 
     if (target != GL_FRAMEBUFFER) {
         synthesizeGLError(GL_INVALID_ENUM, "bindFramebuffer", "invalid target");
         return;
     }
 
     setFramebuffer(target, buffer);
     // This is called both internally and externally (from JavaScript). We only update which wrapper
     // is preserved when it's called from JavaScript.
     if (scriptState) {
-        preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, static_cast<uint32_t>(PreservedFramebuffer), buffer);
+        preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), static_cast<uint32_t>(PreservedFramebuffer), buffer);
     }
 }
 
 void WebGLRenderingContextBase::bindRenderbuffer(ScriptState* scriptState, GLenum target, WebGLRenderbuffer* renderBuffer)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindRenderbuffer", renderBuffer, deleted))
         return;
     if (deleted)
         renderBuffer = 0;
     if (target != GL_RENDERBUFFER) {
         synthesizeGLError(GL_INVALID_ENUM, "bindRenderbuffer", "invalid target");
         return;
     }
     m_renderbufferBinding = renderBuffer;
     contextGL()->BindRenderbuffer(target, objectOrZero(renderBuffer));
-    preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, PreservedRenderbuffer, renderBuffer);
+    preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), PreservedRenderbuffer, renderBuffer);
 
     drawingBuffer()->setRenderbufferBinding(objectOrZero(renderBuffer));
 
     if (renderBuffer)
         renderBuffer->setHasEverBeenBound();
 }
 
 void WebGLRenderingContextBase::bindTexture(ScriptState* scriptState, GLenum target, WebGLTexture* texture)
 {
     bool deleted;
     if (!checkObjectToBeBound("bindTexture", texture, deleted))
         return;
     if (deleted)
         texture = 0;
     if (texture && texture->getTarget() && texture->getTarget() != target) {
         synthesizeGLError(GL_INVALID_OPERATION, "bindTexture", "textures can not be used with multiple targets");
         return;
     }
 
     // ScriptState may be null if this method is called internally
     // during restoration of texture unit bindings. Skip the
     // preserveObjectWrapper work in this case.
-    v8::Local<v8::String> hiddenValueName;
-    ScopedPersistent<v8::Array>* persistentCache = nullptr;
+    V8PrivateProperty::Symbol (*privateSymbolFn)(v8::Isolate* isolate) = nullptr;
     if (target == GL_TEXTURE_2D) {
         m_textureUnits[m_activeTextureUnit].m_texture2DBinding = texture;
 
         if (!m_activeTextureUnit)
             drawingBuffer()->setTexture2DBinding(objectOrZero(texture));
         if (scriptState) {
-            hiddenValueName = V8HiddenValue::webgl2DTextures(scriptState->isolate());
-            persistentCache = &m_2DTextureWrappers;
+            privateSymbolFn = &V8PrivateProperty::getWebGLRenderingContextTextures2D;
         }
     } else if (target == GL_TEXTURE_CUBE_MAP) {
         m_textureUnits[m_activeTextureUnit].m_textureCubeMapBinding = texture;
         if (scriptState) {
-            hiddenValueName = V8HiddenValue::webglCubeMapTextures(scriptState->isolate());
-            persistentCache = &m_cubeMapTextureWrappers;
+            privateSymbolFn = &V8PrivateProperty::getWebGLRenderingContextTexturesCubeMap;
         }
     } else if (isWebGL2OrHigher() && target == GL_TEXTURE_2D_ARRAY) {
         m_textureUnits[m_activeTextureUnit].m_texture2DArrayBinding = texture;
         if (scriptState) {
-            hiddenValueName = V8HiddenValue::webgl2DArrayTextures(scriptState->isolate());
-            persistentCache = &m_2DArrayTextureWrappers;
+            privateSymbolFn = &V8PrivateProperty::getWebGLRenderingContextTextures2DArray;
         }
     } else if (isWebGL2OrHigher() && target == GL_TEXTURE_3D) {
         m_textureUnits[m_activeTextureUnit].m_texture3DBinding = texture;
         if (scriptState) {
-            hiddenValueName = V8HiddenValue::webgl3DTextures(scriptState->isolate());
-            persistentCache = &m_3DTextureWrappers;
+            privateSymbolFn = &V8PrivateProperty::getWebGLRenderingContextTextures3D;
         }
     } else {
         synthesizeGLError(GL_INVALID_ENUM, "bindTexture", "invalid target");
         return;
     }
 
     contextGL()->BindTexture(target, objectOrZero(texture));
     // This is called both internally and externally (from JavaScript). We only update which wrapper
     // is preserved when it's called from JavaScript.
     if (scriptState) {
-        preserveObjectWrapper(scriptState, this, hiddenValueName, persistentCache, m_activeTextureUnit, texture);
+        preserveObjectWrapper(scriptState, this, privateSymbolFn(scriptState->isolate()), m_activeTextureUnit, texture);
     }
     if (texture) {
         texture->setTarget(target);
         m_onePlusMaxNonDefaultTextureUnit = max(m_activeTextureUnit + 1, m_onePlusMaxNonDefaultTextureUnit);
     } else {
         // If the disabled index is the current maximum, trace backwards to find the new max enabled texture index
         if (m_onePlusMaxNonDefaultTextureUnit == m_activeTextureUnit + 1) {
             findNewMaxNonDefaultTextureUnit();
         }
     }
@@ skipping 382 matching lines @@
     return o;
 }
 
 void WebGLRenderingContextBase::setBoundVertexArrayObject(ScriptState* scriptState, WebGLVertexArrayObjectBase* arrayObject)
 {
     if (arrayObject)
         m_boundVertexArrayObject = arrayObject;
     else
         m_boundVertexArrayObject = m_defaultVertexArrayObject;
 
-    preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, static_cast<uint32_t>(PreservedVAO), arrayObject);
+    preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), static_cast<uint32_t>(PreservedVAO), arrayObject);
 }
 
 WebGLShader* WebGLRenderingContextBase::createShader(GLenum type)
 {
     if (isContextLost())
         return nullptr;
     if (type != GL_VERTEX_SHADER && type != GL_FRAGMENT_SHADER) {
         synthesizeGLError(GL_INVALID_ENUM, "createShader", "invalid shader type");
         return nullptr;
     }
@@ skipping 140 matching lines @@
 void WebGLRenderingContextBase::detachShader(ScriptState* scriptState, WebGLProgram* program, WebGLShader* shader)
 {
     if (isContextLost() || !validateWebGLObject("detachShader", program) || !validateWebGLObject("detachShader", shader))
         return;
     if (!program->detachShader(shader)) {
         synthesizeGLError(GL_INVALID_OPERATION, "detachShader", "shader not attached");
         return;
     }
     contextGL()->DetachShader(objectOrZero(program), objectOrZero(shader));
     shader->onDetached(contextGL());
-    preserveObjectWrapper(scriptState, program, V8HiddenValue::webglShaders(scriptState->isolate()), program->getPersistentCache(), static_cast<uint32_t>(shader->type()), nullptr);
+    preserveObjectWrapper(scriptState, program, V8PrivateProperty::getWebGLProgramShaders(scriptState->isolate()), static_cast<uint32_t>(shader->type()), nullptr);
 }
 
 void WebGLRenderingContextBase::disable(GLenum cap)
 {
     if (isContextLost() || !validateCapability("disable", cap))
         return;
     if (cap == GL_STENCIL_TEST) {
         m_stencilEnabled = false;
         applyStencilTest();
         return;
@@ skipping 153 matching lines @@
         return;
     }
     GLuint bufferObject = objectOrZero(buffer);
     if (isWebGL2OrHigher() && attachment == GL_DEPTH_STENCIL_ATTACHMENT) {
         // On ES3, DEPTH_STENCIL_ATTACHMENT is like an alias for DEPTH_ATTACHMENT + STENCIL_ATTACHMENT.
         // We divide it here so in WebGLFramebuffer, we don't have to handle DEPTH_STENCIL_ATTACHMENT in WebGL 2.
         contextGL()->FramebufferRenderbuffer(target, GL_DEPTH_ATTACHMENT, renderbuffertarget, bufferObject);
         contextGL()->FramebufferRenderbuffer(target, GL_STENCIL_ATTACHMENT, renderbuffertarget, bufferObject);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_DEPTH_ATTACHMENT, buffer);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_STENCIL_ATTACHMENT, buffer);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), GL_DEPTH_ATTACHMENT, buffer);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), GL_STENCIL_ATTACHMENT, buffer);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), GL_DEPTH_ATTACHMENT, buffer);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), GL_STENCIL_ATTACHMENT, buffer);
     } else {
         contextGL()->FramebufferRenderbuffer(target, attachment, renderbuffertarget, bufferObject);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, buffer);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), attachment, buffer);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), attachment, buffer);
     }
     applyStencilTest();
 }
 
 void WebGLRenderingContextBase::framebufferTexture2D(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum textarget, WebGLTexture* texture, GLint level)
 {
     if (isContextLost() || !validateFramebufferFuncParameters("framebufferTexture2D", target, attachment))
         return;
     if (texture && !texture->validate(contextGroup(), this)) {
         synthesizeGLError(GL_INVALID_OPERATION, "framebufferTexture2D", "no texture or texture not from this context");
         return;
     }
     // Don't allow the default framebuffer to be mutated; all current
     // implementations use an FBO internally in place of the default
     // FBO.
     WebGLFramebuffer* framebufferBinding = getFramebufferBinding(target);
     if (!framebufferBinding || !framebufferBinding->object()) {
         synthesizeGLError(GL_INVALID_OPERATION, "framebufferTexture2D", "no framebuffer bound");
         return;
     }
     GLuint textureObject = objectOrZero(texture);
     if (isWebGL2OrHigher() && attachment == GL_DEPTH_STENCIL_ATTACHMENT) {
         // On ES3, DEPTH_STENCIL_ATTACHMENT is like an alias for DEPTH_ATTACHMENT + STENCIL_ATTACHMENT.
         // We divide it here so in WebGLFramebuffer, we don't have to handle DEPTH_STENCIL_ATTACHMENT in WebGL 2.
         contextGL()->FramebufferTexture2D(target, GL_DEPTH_ATTACHMENT, textarget, textureObject, level);
         contextGL()->FramebufferTexture2D(target, GL_STENCIL_ATTACHMENT, textarget, textureObject, level);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_DEPTH_ATTACHMENT, textarget, texture, level, 0);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, GL_STENCIL_ATTACHMENT, textarget, texture, level, 0);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), GL_DEPTH_ATTACHMENT, texture);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), GL_STENCIL_ATTACHMENT, texture);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), GL_DEPTH_ATTACHMENT, texture);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), GL_STENCIL_ATTACHMENT, texture);
     } else {
         contextGL()->FramebufferTexture2D(target, attachment, textarget, textureObject, level);
         framebufferBinding->setAttachmentForBoundFramebuffer(target, attachment, textarget, texture, level, 0);
-        preserveObjectWrapper(scriptState, framebufferBinding, V8HiddenValue::webglAttachments(scriptState->isolate()), framebufferBinding->getPersistentCache(), attachment, texture);
+        preserveObjectWrapper(scriptState, framebufferBinding, V8PrivateProperty::getWebGLFramebufferAttachments(scriptState->isolate()), attachment, texture);
     }
     applyStencilTest();
 }
 
 void WebGLRenderingContextBase::frontFace(GLenum mode)
 {
     if (isContextLost())
         return;
     contextGL()->FrontFace(mode);
 }
@@ skipping 210 matching lines @@
                 break;
             }
         }
     }
 
     v8::Local<v8::Value> wrappedExtension = toV8(extension, scriptState->context()->Global(), scriptState->isolate());
 
     if (linkContextToExtension) {
         // Keep the extension's JavaScript wrapper alive as long as the context is alive, so that
         // expando properties that are added to the extension persist.
-        preserveObjectWrapper(scriptState, this, V8HiddenValue::webglExtensions(scriptState->isolate()), &m_extensionWrappers, static_cast<uint32_t>(extension->name()), extension);
+        preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextExtensions(scriptState->isolate()), static_cast<uint32_t>(extension->name()), extension);
     }
 
     return ScriptValue(scriptState, wrappedExtension);
 }
 
 ScriptValue WebGLRenderingContextBase::getFramebufferAttachmentParameter(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum pname)
 {
     if (isContextLost() || !validateFramebufferFuncParameters("getFramebufferAttachmentParameter", target, attachment))
         return ScriptValue::createNull(scriptState);
 
@@ skipping 2304 matching lines @@
         return;
     }
 
     if (m_currentProgram != program) {
         if (m_currentProgram)
             m_currentProgram->onDetached(contextGL());
         m_currentProgram = program;
         contextGL()->UseProgram(objectOrZero(program));
         if (program)
             program->onAttached();
-        preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, static_cast<uint32_t>(PreservedProgram), program);
+        preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), static_cast<uint32_t>(PreservedProgram), program);
     }
 }
 
 void WebGLRenderingContextBase::validateProgram(WebGLProgram* program)
 {
     if (isContextLost() || !validateWebGLObject("validateProgram", program))
         return;
     contextGL()->ValidateProgram(objectOrZero(program));
 }
 
@@ skipping 142 matching lines @@
     if (!validateValueFitNonNegInt32("vertexAttribPointer", "offset", offset))
         return;
     if (!m_boundArrayBuffer) {
         synthesizeGLError(GL_INVALID_OPERATION, "vertexAttribPointer", "no bound ARRAY_BUFFER");
         return;
     }
 
     m_boundVertexArrayObject->setArrayBufferForAttrib(index, m_boundArrayBuffer.get());
     contextGL()->VertexAttribPointer(index, size, type, normalized, stride, reinterpret_cast<void*>(static_cast<intptr_t>(offset)));
     maybePreserveDefaultVAOObjectWrapper(scriptState);
-    preserveObjectWrapper(scriptState, m_boundVertexArrayObject, V8HiddenValue::webglBuffers(scriptState->isolate()), m_boundVertexArrayObject->getPersistentCache(), index, m_boundArrayBuffer);
+    preserveObjectWrapper(scriptState, m_boundVertexArrayObject, V8PrivateProperty::getWebGLVertexArrayObjectBaseBuffers(scriptState->isolate()), index, m_boundArrayBuffer);
 }
 
 void WebGLRenderingContextBase::vertexAttribDivisorANGLE(GLuint index, GLuint divisor)
 {
     if (isContextLost())
         return;
 
     if (index >= m_maxVertexAttribs) {
         synthesizeGLError(GL_INVALID_VALUE, "vertexAttribDivisorANGLE", "index out of range");
         return;
@@ skipping 1215 matching lines @@
     for (int i = startIndex; i >= 0; --i) {
         if (m_textureUnits[i].m_texture2DBinding
             || m_textureUnits[i].m_textureCubeMapBinding) {
             m_onePlusMaxNonDefaultTextureUnit = i + 1;
             return;
         }
     }
     m_onePlusMaxNonDefaultTextureUnit = 0;
 }
 
-void WebGLRenderingContextBase::preserveObjectWrapper(ScriptState* scriptState, ScriptWrappable* sourceObject, v8::Local<v8::String> hiddenValueName, ScopedPersistent<v8::Array>* persistentCache, uint32_t index, ScriptWrappable* targetObject)
+void WebGLRenderingContextBase::preserveObjectWrapper(ScriptState* scriptState, ScriptWrappable* sourceObject, const V8PrivateProperty::Symbol& privateSymbol, uint32_t index, ScriptWrappable* targetObject)
 {
     v8::Isolate* isolate = scriptState->isolate();
-    if (persistentCache->isEmpty()) {
-        // TODO(kbr): eliminate the persistent caches and just use
-        // V8HiddenValue::getHiddenValue. Unfortunately, it's
-        // currently too slow to use. crbug.com/611864
-        persistentCache->set(isolate, v8::Array::New(isolate));
-        V8HiddenValue::setHiddenValue(
-            scriptState,
-            sourceObject->mainWorldWrapper(isolate),
-            hiddenValueName,
-            persistentCache->newLocal(isolate));
-        // It is important to mark the persistent cache as weak
-        // (phantom, actually). Otherwise there will be a reference
-        // cycle between it and its JavaScript wrapper, and currently
-        // there are problems collecting such cycles.
-        persistentCache->setPhantom();
+    v8::Local<v8::Context> context = scriptState->context();
+    v8::Local<v8::Object> sourceWrapper = v8::Local<v8::Object>::Cast(toV8(
+        sourceObject, context->Global(), isolate));
+    v8::Local<v8::Array> array = v8::Local<v8::Array>::Cast(
+        privateSymbol.get(context, sourceWrapper));
+    if (array.IsEmpty()) {
+        array = v8::Array::New(isolate);
+        privateSymbol.set(context, sourceWrapper, array);
     }
-
-    v8::Local<v8::Array> localCache = persistentCache->newLocal(isolate);
     if (targetObject) {
-        v8CallOrCrash(localCache->Set(scriptState->context(), index, targetObject->mainWorldWrapper(isolate)));
+        v8CallOrCrash(array->Set(context, index, toV8(targetObject, context->Global(), isolate)));

[Yuki, 2016/06/02 13:07:22]

This is another reason why this CL is slower. 
|targetObject->mainWorldWrapper()| is faster than |toV8(targetObject)|.

[Ken Russell (switch to Gerrit), 2016/06/03 00:59:19]

Thanks for pointing this out. I tried adding two code paths in this function,
one using mainWorldWrapper and one using toV8. Unfortunately there's still a
performance hit for eliminating the persistent caches. On my Linux workstation
running the WebGL Animometer benchmark it's the difference between 56 ms/frame
and 66 ms/frame. For this reason I reintroduced the persistent caches, but only
use them in the main world.

     } else {
-        v8CallOrCrash(localCache->Set(scriptState->context(), index, v8::Null(isolate)));
+        v8CallOrCrash(array->Set(context, index, v8::Null(isolate)));
     }
 }
 
 void WebGLRenderingContextBase::maybePreserveDefaultVAOObjectWrapper(ScriptState* scriptState)
 {
     ASSERT(scriptState);
 
     if (!m_preservedDefaultVAOObjectWrapper) {
         // The default VAO does not have a JavaScript wrapper created for it, but one is needed to
         // link up the WebGLBuffers associated with the vertex attributes.
         toV8(m_defaultVertexArrayObject, scriptState->context()->Global(), scriptState->isolate());
-        preserveObjectWrapper(scriptState, this, V8HiddenValue::webglMisc(scriptState->isolate()), &m_miscWrappers, static_cast<uint32_t>(PreservedDefaultVAO), m_defaultVertexArrayObject);
+        preserveObjectWrapper(scriptState, this, V8PrivateProperty::getWebGLRenderingContextMisc(scriptState->isolate()), static_cast<uint32_t>(PreservedDefaultVAO), m_defaultVertexArrayObject);
         m_preservedDefaultVAOObjectWrapper = true;
     }
 }
 
 DEFINE_TRACE(WebGLRenderingContextBase::TextureUnitState)
 {
     visitor->trace(m_texture2DBinding);
     visitor->trace(m_textureCubeMapBinding);
     visitor->trace(m_texture3DBinding);
     visitor->trace(m_texture2DArrayBinding);
@@ skipping 50 matching lines @@
         contextGL()->PixelStorei(GL_UNPACK_ALIGNMENT, 1);
 }
 
 void WebGLRenderingContextBase::restoreUnpackParameters()
 {
     if (m_unpackAlignment != 1)
         contextGL()->PixelStorei(GL_UNPACK_ALIGNMENT, m_unpackAlignment);
 }
 
 } // namespace blink