Move NullDraw GL bindings and allow them to be disabled temporarily.

ui/gl/gl_gl_api_implementation.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gl/gl_gl_api_implementation.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 184 matching lines @@
       CustomRenderbufferStorageEXT);
 
   DCHECK(orig_fn.glRenderbufferStorageMultisampleEXTFn == NULL);
   orig_fn.glRenderbufferStorageMultisampleEXTFn =
       fn.glRenderbufferStorageMultisampleEXTFn;
   fn.glRenderbufferStorageMultisampleEXTFn =
       reinterpret_cast<glRenderbufferStorageMultisampleEXTProc>(
       CustomRenderbufferStorageMultisampleEXT);
 }
 
+static void GL_BINDING_CALL NullDrawClearFn(GLbitfield mask) {
+  if (!g_driver_gl.null_draw_bindings_enabled)
+    g_driver_gl.orig_fn.glClearFn(mask);
+}
+
+static void GL_BINDING_CALL
+NullDrawDrawArraysFn(GLenum mode, GLint first, GLsizei count) {
+  if (!g_driver_gl.null_draw_bindings_enabled)
+    g_driver_gl.orig_fn.glDrawArraysFn(mode, first, count);
+}
+
+static void GL_BINDING_CALL NullDrawDrawElementsFn(GLenum mode,
+                                                   GLsizei count,
+                                                   GLenum type,
+                                                   const void* indices) {
+  if (!g_driver_gl.null_draw_bindings_enabled)
+    g_driver_gl.orig_fn.glDrawElementsFn(mode, count, type, indices);
+}
+
+void DriverGL::InitializeNullDrawBindings() {
+  DCHECK(orig_fn.glClearFn == NULL);
+  orig_fn.glClearFn = fn.glClearFn;
+  fn.glClearFn = NullDrawClearFn;
+
+  DCHECK(orig_fn.glDrawArraysFn == NULL);
+  orig_fn.glDrawArraysFn = fn.glDrawArraysFn;
+  fn.glDrawArraysFn = NullDrawDrawArraysFn;
+
+  DCHECK(orig_fn.glDrawElementsFn == NULL);
+  orig_fn.glDrawElementsFn = fn.glDrawElementsFn;
+  fn.glDrawElementsFn = NullDrawDrawElementsFn;
+
+  null_draw_bindings_enabled = true;
+}
+
+bool DriverGL::SetNullDrawBindingsEnabled(bool enabled) {
+  DCHECK(orig_fn.glClearFn != NULL);
+  DCHECK(orig_fn.glDrawArraysFn != NULL);
+  DCHECK(orig_fn.glDrawElementsFn != NULL);
+
+  bool before = null_draw_bindings_enabled;
+  null_draw_bindings_enabled = enabled;
+  return before;
+}
+
 void InitializeStaticGLBindingsGL() {
   g_current_gl_context_tls = new base::ThreadLocalPointer<GLApi>;
   g_driver_gl.InitializeStaticBindings();
   if (!g_real_gl) {
     g_real_gl = new RealGLApi();
     g_trace_gl = new TraceGLApi(g_real_gl);
   }
   g_real_gl->Initialize(&g_driver_gl);
   g_gl = g_real_gl;
   if (CommandLine::ForCurrentProcess()->HasSwitch(
@@ skipping 23 matching lines @@
 }
 
 void InitializeDebugGLBindingsGL() {
   g_driver_gl.InitializeDebugBindings();
 }
 
 void InitializeNullDrawGLBindingsGL() {
   g_driver_gl.InitializeNullDrawBindings();
 }
 
+bool SetNullDrawGLBindingsEnabledGL(bool enabled) {
+  return g_driver_gl.SetNullDrawBindingsEnabled(enabled);
+}
+
 void ClearGLBindingsGL() {
   if (g_real_gl) {
     delete g_real_gl;
     g_real_gl = NULL;
   }
   if (g_trace_gl) {
     delete g_trace_gl;
     g_trace_gl = NULL;
   }
   g_gl = NULL;
@@ skipping 123 matching lines @@
 const GLubyte* VirtualGLApi::glGetStringFn(GLenum name) {
   switch (name) {
     case GL_EXTENSIONS:
       return reinterpret_cast<const GLubyte*>(extensions_.c_str());
     default:
       return driver_->fn.glGetStringFn(name);
   }
 }
 
 }  // namespace gfx