Change GLGetProcAddress typedef to function returning function pointer

ui/gl/gl_mock.h

Index: ui/gl/gl_mock.h
diff --git a/ui/gl/gl_mock.h b/ui/gl/gl_mock.h
index 4a7969a7331cf699db9e8c3ad6836e24c7dc608c..c91c981aace7d682ea489e53ef0fe92a101b51dd 100644
--- a/ui/gl/gl_mock.h
+++ b/ui/gl/gl_mock.h
@@ -14,6 +14,8 @@
 
 namespace gl {
 
+using GLFunctionPointerType = void (*)();
+
 class MockGLInterface {
  public:
   MockGLInterface();
@@ -24,7 +26,8 @@ class MockGLInterface {
   static void SetGLInterface(MockGLInterface* gl_interface);
 
   // Find an entry point to the mock GL implementation.
-  static void* GL_BINDING_CALL GetGLProcAddress(const char* name);
+  static GLFunctionPointerType GL_BINDING_CALL
+  GetGLProcAddress(const char* name);
 
   // Include the auto-generated parts of this class. We split this because
   // it means we can easily edit the non-auto generated parts right here in