Implement OSMesa image transport for TOUCH_UI builds

ui/gfx/gl/gl_context_osmesa.cc

 // Copyright (c) 2011 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 <GL/osmesa.h>
 
 #include "ui/gfx/gl/gl_context_osmesa.h"
 
 #include "base/logging.h"
 #include "ui/gfx/gl/gl_bindings.h"
@@ skipping 11 matching lines @@
 }
 
 bool GLContextOSMesa::Initialize(GLSurface* compatible_surface) {
   DCHECK(!context_);
 
   OSMesaContext share_handle = static_cast<OSMesaContext>(
       share_group() ? share_group()->GetHandle() : NULL);
 
   GLuint format =
       static_cast<GLSurfaceOSMesa*>(compatible_surface)->GetFormat();
+  DCHECK_NE(format, (unsigned)0);
   context_ = OSMesaCreateContextExt(format,
                                     0,  // depth bits
                                     0,  // stencil bits
                                     0,  // accum bits
                                     share_handle);
   if (!context_) {
     LOG(ERROR) << "OSMesaCreateContextExt failed.";
     return false;
   }
 
   return true;
 }
 
 void GLContextOSMesa::Destroy() {
   if (context_) {
     OSMesaDestroyContext(static_cast<OSMesaContext>(context_));
     context_ = NULL;
   }
 }
 
 bool GLContextOSMesa::MakeCurrent(GLSurface* surface) {
   DCHECK(context_);
 
   gfx::Size size = surface->GetSize();
 
-  if (!OSMesaMakeCurrent(static_cast<OSMesaContext>(context_),
+  if (!OSMesaMakeCurrent(context_,
                          surface->GetHandle(),
                          GL_UNSIGNED_BYTE,
                          size.width(),
                          size.height())) {
     LOG(ERROR) << "OSMesaMakeCurrent failed.";
     Destroy();
     return false;
   }
 
   // Row 0 is at the top.
@@ skipping 39 matching lines @@
 void* GLContextOSMesa::GetHandle() {
   return context_;
 }
 
 void GLContextOSMesa::SetSwapInterval(int interval) {
   DCHECK(IsCurrent(NULL));
   LOG(WARNING) << "GLContextOSMesa::SetSwapInterval is ignored.";
 }
 
 }  // namespace gfx