ozone: choose a card useful for display rather than by default

ui/ozone/platform/dri/ozone_platform_gbm.cc

 // Copyright 2014 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/ozone/platform/dri/ozone_platform_gbm.h"
 
 #include <dlfcn.h>
 #include <gbm.h>
 #include <stdlib.h>
 
@@ skipping 31 matching lines @@
 #include "ui/events/ozone/layout/xkb/xkb_evdev_codes.h"
 #include "ui/events/ozone/layout/xkb/xkb_keyboard_layout_engine.h"
 #else
 #include "ui/events/ozone/layout/stub/stub_keyboard_layout_engine.h"
 #endif
 
 namespace ui {
 
 namespace {
 
-const char kDefaultGraphicsCardPath[] = "/dev/dri/card0";
-
 class GlApiLoader {
  public:
   GlApiLoader()
       : glapi_lib_(dlopen("libglapi.so.0", RTLD_LAZY | RTLD_GLOBAL)) {}
 
   ~GlApiLoader() {
     if (glapi_lib_)
       dlclose(glapi_lib_);
   }
 
@@ skipping 84 matching lines @@
         make_scoped_ptr(new StubKeyboardLayoutEngine()));
 #endif
     event_factory_ozone_.reset(new EventFactoryEvdev(
         cursor_.get(), device_manager_.get(),
         KeyboardLayoutEngineManager::GetKeyboardLayoutEngine()));
   }
 
   void InitializeGPU() override {
     gl_api_loader_.reset(new GlApiLoader());
     // Async page flips are supported only on surfaceless mode.
-    gbm_ = new GbmWrapper(base::FilePath(kDefaultGraphicsCardPath));
+    gbm_ = new GbmWrapper(GetFirstDisplayCardPath());
     gbm_->Initialize();
     drm_device_manager_.reset(new DrmDeviceManager(gbm_));
     buffer_generator_.reset(new GbmBufferGenerator());
     screen_manager_.reset(new ScreenManager(buffer_generator_.get()));
     // This makes sure that simple targets that do not handle display
     // configuration can still use the primary display.
     ForceInitializationOfPrimaryDisplay(gbm_, screen_manager_.get());
 
     window_delegate_manager_.reset(new DriWindowDelegateManager());
     if (!surface_factory_ozone_)
@@ skipping 42 matching lines @@
 OzonePlatform* CreateOzonePlatformGbm() {
   base::CommandLine* cmd = base::CommandLine::ForCurrentProcess();
 #if defined(USE_MESA_PLATFORM_NULL)
   // Only works with surfaceless.
   cmd->AppendSwitch(switches::kOzoneUseSurfaceless);
 #endif
   return new OzonePlatformGbm(cmd->HasSwitch(switches::kOzoneUseSurfaceless));
 }
 
 }  // namespace ui