mojo: Convert gles2 to the new thunking system

mojo/public/platform/native/gles2_thunks.h

Index: mojo/public/platform/native/gles2_thunks.h
diff --git a/mojo/public/platform/native/gles2_thunks.h b/mojo/public/platform/native/gles2_thunks.h
new file mode 100644
index 0000000000000000000000000000000000000000..c78ad7d27215341c025c9cd7de3e34df25cf4f2b
--- /dev/null
+++ b/mojo/public/platform/native/gles2_thunks.h
@@ -0,0 +1,73 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_PLATFORM_NATIVE_GLES2_THUNKS_H_
+#define MOJO_PUBLIC_PLATFORM_NATIVE_GLES2_THUNKS_H_
+
+#include <stddef.h>
+
+#include "mojo/public/c/gles2/gles2.h"
+
+// Structure used to bind the GLES2 functions of a DSO to theose of the
+// embedder.
+// This is the ABI between the embedder and the DSO. It can only have new
+// functions added to the end. No other changes are supported.
+#pragma pack(push, 8)
+struct MojoGLES2Thunks {
+  size_t size;  // Should be set to sizeof(MojoGLES2Thunks).
+
+  void (*GLES2Initialize)(const MojoAsyncWaiter* async_waiter);
+  void (*GLES2Terminate)(void);
+  MojoGLES2Context (*GLES2CreateContext)(
+      MojoHandle handle,
+      MojoGLES2ContextLost lost_callback,
+      void* closure);
+  void (*GLES2DestroyContext)(MojoGLES2Context context);
+  void (*GLES2MakeCurrent)(MojoGLES2Context context);
+  void (*GLES2SwapBuffers)(void);
+
+  // TODO(piman): We shouldn't have to leak those 2 interfaces, especially in a
+  // type-unsafe way.
+  void* (*GLES2GetGLES2Interface)(MojoGLES2Context context);
+  void* (*GLES2GetContextSupport)(MojoGLES2Context context);
+
+#define VISIT_GL_CALL(Function, ReturnType, PARAMETERS, ARGUMENTS) \
+  ReturnType (*Function) PARAMETERS;
+#include "mojo/public/c/gles2/gles2_call_visitor_autogen.h"

[viettrungluu, 2014/07/28 22:11:05]

Is this resilient to changes? Is autogen going to generate things in a given
order (and then only add things to the end, and not make any changes)?

Even if so, how would you add any calls "manually"?

[Elliot Glaysher, 2014/07/28 22:21:27]

The functions added from gles2_call_visitor_autogen.h are a frozen API and
changing it would also break PPAPI (if I understand piman@ correctly).

(Somebody (jamesr@?) is working on removing the leaked interface above. The rest
of the interface here is solidifying.)

+#undef VISIT_GL_CALL
+};
+#pragma pack(pop)
+
+// Intended to be called from the embedder. Returns a |MojoCore| initialized
+// to contain pointers to each of the embedder's MojoCore functions.
+inline MojoGLES2Thunks MojoMakeGLES2Thunks() {
+  MojoGLES2Thunks gles2_thunks = {
+    sizeof(MojoGLES2Thunks),
+    MojoGLES2Initialize,
+    MojoGLES2Terminate,
+    MojoGLES2CreateContext,
+    MojoGLES2DestroyContext,
+    MojoGLES2MakeCurrent,
+    MojoGLES2SwapBuffers,
+    MojoGLES2GetGLES2Interface,
+    MojoGLES2GetContextSupport,
+#define VISIT_GL_CALL(Function, ReturnType, PARAMETERS, ARGUMENTS) \
+    gl##Function,
+#include "mojo/public/c/gles2/gles2_call_visitor_autogen.h"
+#undef VISIT_GL_CALL
+  };
+
+  return gles2_thunks;
+}
+
+// Use this type for the function found by dynamically discovering it in
+// a DSO linked with mojo_system. For example:
+// MojoSetGLES2ThunksFn mojo_set_gles2_thunks_fn =
+//     reinterpret_cast<MojoSetGLES2ThunksFn>(app_library.GetFunctionPointer(
+//         "MojoSetGLES2Thunks"));
+// The expected size of |gles2_thunks} is returned.
+// The contents of |gles2_thunks| are copied.
+typedef size_t (*MojoSetGLES2ThunksFn)(const MojoGLES2Thunks* gles2_thunks);
+
+#endif  // MOJO_PUBLIC_PLATFORM_NATIVE_GLES2_THUNKS_H_