implement getBufferSubDataAsync prototype

third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h

Index: third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
diff --git a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
index 295b49b80d4f679f31c9f7f492415611ea240519..b11ce0e495ae704b81eb37d9f6c9e9ed1a458226 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
+++ b/third_party/WebKit/Source/modules/webgl/WebGL2RenderingContextBase.h
@@ -5,6 +5,7 @@
 #ifndef WebGL2RenderingContextBase_h
 #define WebGL2RenderingContextBase_h
 
+#include "bindings/core/v8/ScriptPromise.h"
 #include "modules/webgl/WebGLExtension.h"
 #include "modules/webgl/WebGLRenderingContextBase.h"
 #include <memory>
@@ -27,6 +28,8 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
  public:
   ~WebGL2RenderingContextBase() override;
 
+  void destroyContext() override;
+
   /* Buffer objects */
   void bufferData(GLenum, DOMArrayBufferView*, GLenum, GLuint, GLuint);
   void bufferSubData(GLenum, GLintptr, DOMArrayBufferView*, GLuint, GLuint);
@@ -42,6 +45,12 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
 
   void copyBufferSubData(GLenum, GLenum, long long, long long, long long);
   void getBufferSubData(GLenum, long long, DOMArrayBufferView*, GLuint, GLuint);
+  ScriptPromise getBufferSubDataAsync(ScriptState*,
+                                      GLenum,
+                                      GLintptr,
+                                      DOMArrayBufferView*,
+                                      GLuint,
+                                      GLuint);
 
   /* Framebuffer objects */
   bool validateTexFuncLayer(const char*, GLenum texTarget, GLint layer);
@@ -807,6 +816,32 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
                                         GLenum target) override;
   bool validateBufferDataUsage(const char* functionName, GLenum usage) override;
 
+  class GetBufferSubDataAsyncCallback
+      : public RefCounted<GetBufferSubDataAsyncCallback> {
+   private:
+    WeakPersistent<WebGL2RenderingContextBase> context;
+    Persistent<DOMArrayBufferView> dstData;
+    Persistent<ScriptPromiseResolver> resolver;
+    void* subBaseAddress;
+    void* mappedData;
+    long long subByteLength;
+
+   public:
+    GetBufferSubDataAsyncCallback(WebGL2RenderingContextBase*,
+                                  DOMArrayBufferView*,
+                                  ScriptPromiseResolver*,
+                                  void*,
+                                  void*,
+                                  long long);
+    void destroy();
+    static void resolve(GetBufferSubDataAsyncCallback*);
+  };
+
+  std::set<GetBufferSubDataAsyncCallback*> m_getBufferSubDataAsyncCallbacks;
+
+  void registerGetBufferSubDataAsyncCallback(GetBufferSubDataAsyncCallback*);
+  void unregisterGetBufferSubDataAsyncCallback(GetBufferSubDataAsyncCallback*);
+
   bool canUseTexImageByGPU(TexImageFunctionID,
                            GLint internalformat,
                            GLenum type) override;