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

gpu/command_buffer/service/program_manager.cc

Index: gpu/command_buffer/service/program_manager.cc
diff --git a/gpu/command_buffer/service/program_manager.cc b/gpu/command_buffer/service/program_manager.cc
index 92615df4490552e4c39fca615be060442724f4b7..6cbff3ba7e800fbc0cecb35af2b8ac2e02939bda 100644
--- a/gpu/command_buffer/service/program_manager.cc
+++ b/gpu/command_buffer/service/program_manager.cc
@@ -1383,7 +1383,7 @@ bool Program::Link(ShaderManager* manager,
     ExecuteProgramOutputBindCalls();
 
     before_time = TimeTicks::Now();
-    if (cache && gl::g_driver_gl.ext.b_GL_ARB_get_program_binary) {
+    if (cache && gl::g_current_gl_driver->ext.b_GL_ARB_get_program_binary) {
       glProgramParameteri(service_id(),
                           PROGRAM_BINARY_RETRIEVABLE_HINT,
                           GL_TRUE);