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

gpu/ipc/service/image_transport_surface_overlay_mac.mm

Index: gpu/ipc/service/image_transport_surface_overlay_mac.mm
diff --git a/gpu/ipc/service/image_transport_surface_overlay_mac.mm b/gpu/ipc/service/image_transport_surface_overlay_mac.mm
index 5c570f7d346c5e3839ba8fcb02686fd48453ab93..85b432909e0733c7728185c40441fa9bf410b1e8 100644
--- a/gpu/ipc/service/image_transport_surface_overlay_mac.mm
+++ b/gpu/ipc/service/image_transport_surface_overlay_mac.mm
@@ -41,7 +41,6 @@ typedef void* GLeglImageOES;
 #include "ui/gl/gl_fence.h"
 #include "ui/gl/gl_image_io_surface.h"
 #include "ui/gl/gpu_switching_manager.h"
-#include "ui/gl/scoped_api.h"
 #include "ui/gl/scoped_cgl.h"
 
 namespace {
@@ -115,7 +114,6 @@ bool ImageTransportSurfaceOverlayMac::Initialize(gl::GLSurfaceFormat format) {
 void ImageTransportSurfaceOverlayMac::Destroy() {
   ca_layer_tree_coordinator_.reset();
   if (previous_frame_fence_) {
-    gl::ScopedSetGLToRealGLApi scoped_set_gl_api;
     // Ensure we are using the context with which the fence was created.
     gl::ScopedCGLSetCurrentContext scoped_set_current(fence_context_obj_);
     CheckGLErrors("Before destroy fence");
@@ -187,7 +185,6 @@ gfx::SwapResult ImageTransportSurfaceOverlayMac::SwapBuffersInternal(
   // If supported, use GLFence to ensure that we haven't gotten more than one
   // frame ahead of GL.
   if (gl::GLFence::IsSupported()) {
-    gl::ScopedSetGLToRealGLApi scoped_set_gl_api;

[jbauman, 2017/01/18 21:32:09]

Won't it be problematic if this code uses the virtual context rather than the
real context?

[Geoff Lang, 2017/01/19 15:40:06]

Virtual contexts still use the RealGLApi.  I talked to ccameron about the usage
of ScopedSetGLToRealGLApi here and in the other mac files, they were used to
make sure that the NoContextGLApi wasn't bound when making these calls.  I found
that this was only possible in the Destroy functions and I tried to handle that
in other ways, GLContextCGL now makes sure that it is current while it destroys
its resources.

     CheckGLErrors("Before fence/flush");
 
     // If we have gotten more than one frame ahead of GL, wait for the previous
@@ -234,7 +231,6 @@ gfx::SwapResult ImageTransportSurfaceOverlayMac::SwapBuffersInternal(
   } else {
     // GLFence isn't supported - issue a glFinish on each frame to ensure
     // there is backpressure from GL.
-    gl::ScopedSetGLToRealGLApi scoped_set_gl_api;
     TRACE_EVENT0("gpu", "ImageTransportSurfaceOverlayMac::glFinish");
     CheckGLErrors("Before finish");
     glFinish();