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

ui/gl/gl_surface_osmesa.cc

Index: ui/gl/gl_surface_osmesa.cc
diff --git a/ui/gl/gl_surface_osmesa.cc b/ui/gl/gl_surface_osmesa.cc
index 7994eec379187df5b0838ab1f7749615d8fff3ae..9a556bc9982d528dcfb40aa81fc08e861e454b27 100644
--- a/ui/gl/gl_surface_osmesa.cc
+++ b/ui/gl/gl_surface_osmesa.cc
@@ -6,6 +6,7 @@
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_context.h"
 #include "ui/gl/gl_surface_osmesa.h"
+#include "ui/gl/scoped_make_current.h"
 
 namespace gfx {
 
@@ -23,10 +24,15 @@ void GLSurfaceOSMesa::Destroy() {
 }
 
 bool GLSurfaceOSMesa::Resize(const gfx::Size& new_size) {
+  scoped_ptr<ui::ScopedMakeCurrent> scoped_make_current;
   GLContext* current_context = GLContext::GetCurrent();
-  bool was_current = current_context && current_context->IsCurrent(this);
-  if (was_current)
+  bool was_current =
+      current_context && current_context->IsCurrent(this);
+  if (was_current) {
+    scoped_make_current.reset(
+        new ui::ScopedMakeCurrent(current_context, this));
     current_context->ReleaseCurrent(this);
+  }
 
   // Preserve the old buffer.
   scoped_ptr<int32[]> old_buffer(buffer_.release());
@@ -48,9 +54,6 @@ bool GLSurfaceOSMesa::Resize(const gfx::Size& new_size) {
 
   size_ = new_size;
 
-  if (was_current)
-    return current_context->MakeCurrent(this);
-
   return true;
 }