Improve GL helpers.

mojo/gpu/gl_context.h

Index: mojo/gpu/gl_context.h
diff --git a/mojo/gpu/gl_context.h b/mojo/gpu/gl_context.h
index 2ccdaaddafe88014f5109283e8942f4eaa474e8a..a557fdb83c666f6d28ffcbe6b2856986b6d3252a 100644
--- a/mojo/gpu/gl_context.h
+++ b/mojo/gpu/gl_context.h
@@ -12,6 +12,7 @@
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 
 namespace mojo {
+class ApplicationConnector;
 class CommandBuffer;
 using CommandBufferPtr = InterfacePtr<CommandBuffer>;
 class Shell;
@@ -26,7 +27,11 @@ class GLContext {
     virtual ~Observer();
   };
 
-  static base::WeakPtr<GLContext> Create(Shell* shell);
+  // Creates an offscreen GL context.
+  static base::WeakPtr<GLContext> CreateOffscreen(
+      ApplicationConnector* connector);
+
+  // Creates a GL context from a command buffer.
   static base::WeakPtr<GLContext> CreateFromCommandBuffer(
       CommandBufferPtr command_buffer);