Ensure GL initialization only happens once, and provide common init path

ui/compositor/test/default_context_factory.cc

Index: ui/compositor/test/default_context_factory.cc
diff --git a/ui/compositor/test/default_context_factory.cc b/ui/compositor/test/default_context_factory.cc
index 4839e1f19a78a8910d37520891bf183e49140098..21c004dfc185178ec84d7eb56561f9b3de5093c9 100644
--- a/ui/compositor/test/default_context_factory.cc
+++ b/ui/compositor/test/default_context_factory.cc
@@ -15,20 +15,12 @@
 namespace ui {
 
 DefaultContextFactory::DefaultContextFactory() {
+  DCHECK_NE(gfx::GetGLImplementation(), gfx::kGLImplementationNone);
 }
 
 DefaultContextFactory::~DefaultContextFactory() {
 }
 
-bool DefaultContextFactory::Initialize() {
-  if (!gfx::GLSurface::InitializeOneOff() ||
-      gfx::GetGLImplementation() == gfx::kGLImplementationNone) {
-    LOG(ERROR) << "Could not load the GL bindings";
-    return false;
-  }
-  return true;
-}
-
 scoped_ptr<cc::OutputSurface> DefaultContextFactory::CreateOutputSurface(
     Compositor* compositor, bool software_fallback) {
   DCHECK(!software_fallback);