Implement --ozone-platform flag to select OzonePlatform implementation at runtime

ui/base/ozone/ozone_platform.cc

 // Copyright (c) 2013 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 "base/command_line.h"
 #include "base/logging.h"
 #include "ui/base/ozone/ozone_platform.h"
+#include "ui/base/ozone/ozone_platform_list.h"
+#include "ui/base/ozone/ozone_switches.h"
 
 namespace ui {
 
+namespace {
+
+OzonePlatform* CreatePlatform(const std::string& platform_name) {
+  for (int i = 0; i < kOzonePlatformCount; ++i)

[rjkroege, 2013/10/28 16:02:15]

default maps to the first element in the list right?

In which case, why not move the platform_name == "default" out of the loop? I
think that would be easier to read.

[spang, 2013/10/28 16:27:39]

Done.

+    if (platform_name == kOzonePlatforms[i].name || platform_name == "default")
+      return kOzonePlatforms[i].constructor();
+
+  LOG(FATAL) << "Invalid ozone platform: " << platform_name;
+  return NULL;  // not reached
+}
+
+std::string GetRequestedPlatform() {

[rjkroege, 2013/10/28 16:02:15]

maybe add a comment here saying "returns the name of the ozone platform" or
something

[spang, 2013/10/28 16:27:39]

Done.

+  if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kOzonePlatform))
+    return "default";
+  return CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+      switches::kOzonePlatform);
+}
+
+}  // namespace
+
 OzonePlatform::OzonePlatform() {}
 
 OzonePlatform::~OzonePlatform() {
   gfx::SurfaceFactoryOzone::SetInstance(NULL);
   ui::EventFactoryOzone::SetInstance(NULL);
 }
 
 // static
 OzonePlatform* OzonePlatform::Create() {
-  OzonePlatform* platform = CreateDefaultOzonePlatform();
+  OzonePlatform* platform = CreatePlatform(GetRequestedPlatform());
 
   gfx::SurfaceFactoryOzone::SetInstance(platform->GetSurfaceFactoryOzone());
   ui::EventFactoryOzone::SetInstance(platform->GetEventFactoryOzone());
 
   return platform;
 }
 
 }  // namespace ui