GPU: Keep track of the last real context and real surface made current.

ui/gl/gl_context.cc

Index: ui/gl/gl_context.cc
diff --git a/ui/gl/gl_context.cc b/ui/gl/gl_context.cc
index e26f75943b6564db26bb153f370fe278012f9bfa..3093053e64ab5006b849670d20d4aebcde483c81 100644
--- a/ui/gl/gl_context.cc
+++ b/ui/gl/gl_context.cc
@@ -20,6 +20,9 @@ namespace gfx {
 namespace {
 base::LazyInstance<base::ThreadLocalPointer<GLContext> >::Leaky
     current_context_ = LAZY_INSTANCE_INITIALIZER;
+
+base::LazyInstance<base::ThreadLocalPointer<GLContext> >::Leaky
+    current_real_context_ = LAZY_INSTANCE_INITIALIZER;
 }  // namespace
 
 GLContext::GLContext(GLShareGroup* share_group) : share_group_(share_group) {
@@ -90,7 +93,16 @@ GLContext* GLContext::GetCurrent() {
   return current_context_.Pointer()->Get();
 }
 
+GLContext* GLContext::GetRealCurrent() {
+  return current_real_context_.Pointer()->Get();
+}
+
 void GLContext::SetCurrent(GLContext* context, GLSurface* surface) {
+  DCHECK_EQ(!context, !surface);
+  if (!context || !context->IsVirtualContext()) {

[epenner, 2013/05/28 21:33:53]

One drive-by comment:

If we keep keep track of the real context, I think we need to always set it here
(for example by grabbing the real context from the virtual context). For example
if there is several real contexts, each backing several virtual contexts, we
still want to change the real context if it has changed.

I believe Gregg mentioned pepper as a use-case where we would use one real
context for each plugin type, with virtual for each plugin instance.

[jonathan.backer, 2013/05/31 17:21:40]

By only changing current_real_context_ when the real context is made current,
current_real_context_ reflects a GL call that was made. I think it's easier to
reason if that invariant is maintained.

AFAICT, as part of the making the virtual context current, the real context will
be made current. We've got a DCHECK in VirtualGLApi::MakeCurrent to this affect.
Sorry. I may be mistaken (I often am), but I don't see how this precludes that.
There may need to be some changes at the gl_gl_api_implementation level.

+    current_real_context_.Pointer()->Set(context);
+    GLSurface::SetRealCurrent(surface);
+  }
   current_context_.Pointer()->Set(context);
   GLSurface::SetCurrent(surface);
 }
@@ -128,7 +140,10 @@ void GLContext::SetupForVirtualization() {
 bool GLContext::MakeVirtuallyCurrent(
     GLContext* virtual_context, GLSurface* surface) {
   DCHECK(virtual_gl_api_);
-  return virtual_gl_api_->MakeCurrent(virtual_context, surface);
+  bool result = virtual_gl_api_->MakeCurrent(virtual_context, surface);
+  if (result)
+    SetCurrent(virtual_context, surface);
+  return result;
 }
 
 void GLContext::OnDestroyVirtualContext(GLContext* virtual_context) {
@@ -140,4 +155,8 @@ void GLContext::SetRealGLApi() {
   SetGLToRealGLApi();
 }
 
+bool GLContext::IsVirtualContext() {
+  return false;
+}
+
 }  // namespace gfx