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

gpu/command_buffer/service/context_group.cc

Index: gpu/command_buffer/service/context_group.cc
diff --git a/gpu/command_buffer/service/context_group.cc b/gpu/command_buffer/service/context_group.cc
index a78799d7e3a458f10b1286e75eb0ac114fec5f05..291763b0f40c595160674c398c9e30bea742a158 100644
--- a/gpu/command_buffer/service/context_group.cc
+++ b/gpu/command_buffer/service/context_group.cc
@@ -553,9 +553,11 @@ void ContextGroup::Destroy(GLES2Decoder* decoder, bool have_context) {
 
   memory_tracker_ = NULL;
 
-  passthrough_resources_->Destroy(have_context);
-  passthrough_resources_.reset();
-  ReportProgress();
+  if (passthrough_resources_) {
+    passthrough_resources_->Destroy(have_context);
+    passthrough_resources_.reset();
+    ReportProgress();
+  }
 }
 
 uint32_t ContextGroup::GetMemRepresented() const {