Allow use of EGL in browser tests with --use-gl=egl.

ui/gl/gl_surface.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_surface.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 24 matching lines @@
 
   std::vector<GLImplementation> allowed_impls;
   GetAllowedGLImplementations(&allowed_impls);
   DCHECK(!allowed_impls.empty());
 
   CommandLine* cmd = CommandLine::ForCurrentProcess();
 
   // The default implementation is always the first one in list.
   GLImplementation impl = allowed_impls[0];
   bool fallback_to_osmesa = false;
-  if (cmd->HasSwitch(switches::kUseGL)) {
+  if (cmd->HasSwitch(switches::kOverrideUseGLWithOSMesaForTests)) {
+    impl = kGLImplementationOSMesaGL;
+  } else if (cmd->HasSwitch(switches::kUseGL)) {
     std::string requested_implementation_name =
         cmd->GetSwitchValueASCII(switches::kUseGL);
     if (requested_implementation_name == "any") {
       fallback_to_osmesa = true;
     } else if (requested_implementation_name == "swiftshader") {
       impl = kGLImplementationEGLGLES2;
     } else {
       impl = GetNamedGLImplementation(requested_implementation_name);
       if (std::find(allowed_impls.begin(),
                     allowed_impls.end(),
@@ skipping 272 matching lines @@
   return surface_->GetFormat();
 }
 
 VSyncProvider* GLSurfaceAdapter::GetVSyncProvider() {
   return surface_->GetVSyncProvider();
 }
 
 GLSurfaceAdapter::~GLSurfaceAdapter() {}
 
 }  // namespace gfx