Refactor GL bindings so there is no global GLApi or DriverGL.

ui/gl/gl_context_cgl.cc

 // Copyright (c) 2012 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 "ui/gl/gl_context_cgl.h"
 
 #include <OpenGL/CGLRenderers.h>
 #include <OpenGL/CGLTypes.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/trace_event.h"
 #include "ui/gl/gl_bindings.h"
+#include "ui/gl/gl_gl_api_implementation.h"
 #include "ui/gl/gl_implementation.h"
 #include "ui/gl/gl_surface.h"
 #include "ui/gl/gpu_switching_manager.h"
 #include "ui/gl/scoped_cgl.h"
 #include "ui/gl/yuv_to_rgb_converter.h"
 
 namespace gl {
 
 namespace {
 
@@ skipping 112 matching lines @@
   // Contexts that prefer integrated gpu are known to use only the subset of GL
   // that can be safely migrated between the iGPU and the dGPU. Mark those
   // contexts as safe to forcibly transition between the GPUs by default.
   // http://crbug.com/180876, http://crbug.com/227228
   safe_to_force_gpu_switch_ = gpu_preference == PreferIntegratedGpu;
   return true;
 }
 
 void GLContextCGL::Destroy() {
   if (yuv_to_rgb_converter_) {
+    // If this context is not current, bind this context's API so that the YUV
+    // converter can safely destruct
+    GLContext* current_context = GetRealCurrent();
+    if (current_context != this) {
+      SetCurrentGL(GetCurrentGL());
+    }
+
     ScopedCGLSetCurrentContext(static_cast<CGLContextObj>(context_));
     yuv_to_rgb_converter_.reset();
+
+    // Rebind the current context's API if needed.
+    if (current_context && current_context != this) {
+      SetCurrentGL(current_context->GetCurrentGL());
+    }
   }
   if (discrete_pixelformat_) {
     if (base::MessageLoop::current() != nullptr) {
       // Delay releasing the pixel format for 10 seconds to reduce the number of
       // unnecessary GPU switches.
       base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
           FROM_HERE, base::Bind(&CGLReleasePixelFormat, discrete_pixelformat_),
           base::TimeDelta::FromSeconds(10));
     } else {
       CGLReleasePixelFormat(discrete_pixelformat_);
@@ skipping 65 matching lines @@
   ScopedReleaseCurrent release_current;
   TRACE_EVENT0("gpu", "GLContextCGL::MakeCurrent");
 
   if (CGLSetCurrentContext(
       static_cast<CGLContextObj>(context_)) != kCGLNoError) {
     LOG(ERROR) << "Unable to make gl context current.";
     return false;
   }
 
   // Set this as soon as the context is current, since we might call into GL.
-  SetRealGLApi();
+  BindGLApi();
 
   SetCurrent(surface);
   InitializeDynamicBindings();
 
   if (!surface->OnMakeCurrent(this)) {
     LOG(ERROR) << "Unable to make gl context current.";
     return false;
   }
 
   release_current.Cancel();
@@ skipping 37 matching lines @@
 
 GLContextCGL::~GLContextCGL() {
   Destroy();
 }
 
 GpuPreference GLContextCGL::GetGpuPreference() {
   return gpu_preference_;
 }
 
 }  // namespace gl