osr: Implement shared texture support (fixes #1006, fixes #2575)

Adds support for the OnAcceleratedPaint callback. Verified to work
on macOS and Windows. Linux support is present but not implemented
for cefclient, so it is not verified to work.

To test:
Run `cefclient --off-screen-rendering-enabled --shared-texture-enabled`

libcef_dll/ctocpp/render_handler_ctocpp.h

@@ -9,7 +9,7 @@
 // implementations. See the translator.README.txt file in the tools directory
 // for more information.
 //
-// $hash=b1028055c90d484e6548009d8bb6e69e06ac1d17$
+// $hash=ae20df54c0accee56380672fa4c7e501a0037348$
 //
 
 #ifndef CEF_LIBCEF_DLL_CTOCPP_RENDER_HANDLER_CTOCPP_H_
@@ -56,7 +56,7 @@ class CefRenderHandlerCToCpp
   void OnAcceleratedPaint(CefRefPtr<CefBrowser> browser,
                           PaintElementType type,
                           const RectList& dirtyRects,
-                          void* shared_handle) override;
+                          const CefAcceleratedPaintInfo& info) override;
   void GetTouchHandleSize(CefRefPtr<CefBrowser> browser,
                           cef_horizontal_alignment_t orientation,
                           CefSize& size) override;