Add GetProcAddress to OpenGL control interface

mojo/gles2/control_thunks_impl.cc

 // Copyright 2015 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.
 
 #include "mojo/gles2/control_thunks_impl.h"
 
+#include "gpu/command_buffer/client/gles2_lib.h"
 #include "mojo/gles2/gles2_context.h"
 #include "mojo/public/cpp/system/message_pipe.h"
 
 namespace gles2 {
 
 // static
 ControlThunksImpl* ControlThunksImpl::Get() {
   static base::LazyInstance<ControlThunksImpl>::Leaky thunks;
   return thunks.Pointer();
 }
@@ skipping 28 matching lines @@
 }
 
 void ControlThunksImpl::ResizeSurface(uint32_t width, uint32_t height) {
   current_context_tls_.Get()->interface()->ResizeCHROMIUM(width, height, 1.f);
 }
 
 void ControlThunksImpl::SwapBuffers() {
   current_context_tls_.Get()->interface()->SwapBuffers();
 }
 
+MGLFunctionPointerType ControlThunksImpl::GetProcAddress(const char* name) {
+  return gles2::GetGLFunctionPointer(name);

[jamesr, 2015/09/21 19:38:50]

this will return things that the underlying library exposes but that we've
chosen not to expose through our thunks.  I don't think we want to do that -
it's too broad and it makes it hard to know what is exposed and what's not.
instead, we should only expose the functions that exist in the autogen headers
used when building the system.  In practice this means going through the autogen
tables to map names to exposed functions and return those. this could just be a
big chain of strncmp()s driven by the autogen header's macros for now and we can
make it a more efficient lookup later if we want (or not).

[Petr Hosek, 2015/09/22 20:06:54]

Done.

+}
+
 void* ControlThunksImpl::GetGLES2Interface(MGLContext context) {
   GLES2Context* client = reinterpret_cast<GLES2Context*>(context);
   DCHECK(client);
   return client->interface();
 }
 
 void ControlThunksImpl::SignalSyncPoint(
     uint32_t sync_point,
     MGLSignalSyncPointCallback callback,
     void* closure) {
   current_context_tls_.Get()->context_support()->SignalSyncPoint(
       sync_point, base::Bind(callback, closure));
 }
 
 gpu::gles2::GLES2Interface* ControlThunksImpl::CurrentGLES2Interface() {
   if (!current_context_tls_.Get())
     return nullptr;
   return current_context_tls_.Get()->interface();
 }
 
 ControlThunksImpl::ControlThunksImpl() {
 }
 
 ControlThunksImpl::~ControlThunksImpl() {
 }
 
 }  // namespace gles2