gpu: Fix corrupted state due to virtual MakeCurrent race.

gpu/command_buffer/service/gl_context_virtual.cc

Index: gpu/command_buffer/service/gl_context_virtual.cc
diff --git a/gpu/command_buffer/service/gl_context_virtual.cc b/gpu/command_buffer/service/gl_context_virtual.cc
index 938d811d50be5d04ad98485b9aadc1ebf77b729c..8051e06c3b935105f84f1863a7c524fb04783183 100644
--- a/gpu/command_buffer/service/gl_context_virtual.cc
+++ b/gpu/command_buffer/service/gl_context_virtual.cc
@@ -30,12 +30,20 @@ bool GLContextVirtual::Initialize(
 
   display_ = static_cast<gfx::Display*>(compatible_surface->GetDisplay());
 
-  if (!shared_context_->MakeCurrent(compatible_surface))
-    return false;
+  // Virtual contexts obviously can't make a context that is compatible
+  // with the surface (the context already exists), but we do need to
+  // make a context current for SetupForVirtualization() below.
+  if (!IsCurrent(compatible_surface)) {
+    if (!shared_context_->MakeCurrent(compatible_surface)) {
+      // This is likely an error. The real context should be made as
+      // compatible with all required surfaces when it was created.
+      LOG(ERROR) << "Failed MakeCurrent(compatible_surface)";
+      return false;
+    }
+  }
 
   shared_context_->SetupForVirtualization();
-
-  shared_context_->ReleaseCurrent(compatible_surface);
+  shared_context_->MakeVirtuallyCurrent(this, compatible_surface);
   return true;
 }
 
@@ -46,9 +54,12 @@ void GLContextVirtual::Destroy() {
 }
 
 bool GLContextVirtual::MakeCurrent(gfx::GLSurface* surface) {
-  if (decoder_.get() && decoder_->initialized())
+  // TODO(epenner): We should avoid bypassing MakeVirtuallyCurrent() below
+  // (return false or DCHECK when !decoder). To do this we must reorder
+  // tear-down in GpuCommandBufferStub::Destroy().
+  if (decoder_.get())
     shared_context_->MakeVirtuallyCurrent(this, surface);
-  else
+  else if (!IsCurrent(surface))
     shared_context_->MakeCurrent(surface);
   return true;
 }
@@ -59,18 +70,14 @@ void GLContextVirtual::ReleaseCurrent(gfx::GLSurface* surface) {
 }
 
 bool GLContextVirtual::IsCurrent(gfx::GLSurface* surface) {
-  bool context_current = shared_context_->IsCurrent(NULL);
-  if (!context_current)
-    return false;
-
-  if (!surface)
-    return true;
-
-  gfx::GLSurface* current_surface = gfx::GLSurface::GetCurrent();
-  return surface->GetBackingFrameBufferObject() ||
-      surface->IsOffscreen() ||
-      (current_surface &&
-       current_surface->GetHandle() == surface->GetHandle());
+  // If it's a real surface it needs to be current.
+  if (surface &&
+      !surface->GetBackingFrameBufferObject() &&
+      !surface->IsOffscreen())
+    return shared_context_->IsCurrent(surface);
+
+  // Otherwise, only insure the context itself is current.
+  return shared_context_->IsCurrent(NULL);
 }
 
 void* GLContextVirtual::GetHandle() {