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 23479a91c40c872683f81e18756676d6259718c6..dacce91ebb7852be55d6c224138a406d69cd159d 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);
@@ -43,6 +46,12 @@ 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);
@@ -811,6 +820,32 @@ class WebGL2RenderingContextBase : public WebGLRenderingContextBase {
                                         GLenum target) override;
   bool validateBufferDataUsage(const char* functionName, GLenum usage) override;
 
+  class GetBufferSubDataAsyncCallback
+      : public RefCounted<GetBufferSubDataAsyncCallback> {

[esprehn, 2016/10/08 03:02:49]

Does this need to be a nested class?

[Kai Ninomiya, 2016/10/11 01:34:14]

I'll simplify this.

+   private:

[Ken Russell (switch to Gerrit), 2016/10/10 22:21:30]

Per the Google C++ style guide at
https://google.github.io/styleguide/cppguide.html#Declaration_Order , the public
members should go first in the class.

[Kai Ninomiya, 2016/10/11 01:34:14]

Done.

+    WeakPersistent<WebGL2RenderingContextBase> context;
+    Persistent<DOMArrayBufferView> dstData;

[esprehn, 2016/10/08 03:02:49]

We don't generally abbreviate in blink, does the spec use "dst" ?

[Kai Ninomiya, 2016/10/11 01:34:14]

Yes, the spec uses "dst." However, it does not need to be abbreviated this way
here, so I'm going to rename several things here.

+    Persistent<ScriptPromiseResolver> resolver;
+    void* subBaseAddress;

[Ken Russell (switch to Gerrit), 2016/10/10 22:21:30]

These variables could use some comments. Also, please group them together
according to relationship. dstData, subBaseAddress and subByteLength should be
together. mappedData should come either before or after, and have a separate
comment.

+    void* mappedData;
+    long long subByteLength;

[esprehn, 2016/10/08 03:02:49]

Very few things in blink can actually handle something as big as a long long,
ex. JS can't even represent that. What does this get used for?

[Ken Russell (switch to Gerrit), 2016/10/10 22:21:30]

It represents the amount of data read back from the GPU to the CPU. It could use
an OpenGL typedef like GLuint, which is what's used in the IDL and which is
typedef'd there to something representable in JavaScript. Kai, would you make
that change?

[Kai Ninomiya, 2016/10/11 01:34:14]

esprehn: Excellent point, I agree. If it's alright, I'm going to handle this in
another CL. This type comes from existing code (validateSubSourceAndGetData) and
I will need to change it and all of its (four) usages at once, as well as
closely inspect changes to validateSubSourceAndGetData, which is a security
sensitive range validation function.

+
+   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;