Read EDID for the 1st display for startup

ui/ozone/platform/dri/native_display_delegate_proxy.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/native_display_delegate_proxy.h"
 
 #include <stdio.h>
 
 #include "base/logging.h"
+#include "base/threading/thread_restrictions.h"
 #include "ui/display/types/display_snapshot.h"
 #include "ui/display/types/native_display_observer.h"
 #include "ui/events/ozone/device/device_event.h"
 #include "ui/events/ozone/device/device_manager.h"
 #include "ui/ozone/common/display_snapshot_proxy.h"
 #include "ui/ozone/common/display_util.h"
 #include "ui/ozone/common/gpu/ozone_gpu_messages.h"
 #include "ui/ozone/platform/dri/display_manager.h"
 #include "ui/ozone/platform/dri/dri_gpu_platform_support_host.h"
 
@@ skipping 36 matching lines @@
   device_manager_->RemoveObserver(this);
   proxy_->UnregisterHandler(this);
 }
 
 void NativeDisplayDelegateProxy::Initialize() {
   device_manager_->AddObserver(this);
   device_manager_->ScanDevices(this);
 
   if (!displays_.empty())
     return;
+  DisplaySnapshot_Params params;
+  bool success = false;
+  {
+    // The file generated by frecon that contains EDID for the 1st display.
+    const base::FilePath kEDIDFile("/tmp/display_info.bin");
 
-  DisplaySnapshot_Params params = CreateSnapshotFromCommandLine();
-  if (params.type != DISPLAY_CONNECTION_TYPE_NONE) {
+    // Just read it on current thread as this is necessary information
+    // to start. This access only tmpfs, which is fast.
+    // TODO(dnicoara|oshima): crbug.com/450886.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    success = CreateSnapshotFromEDIDFile(kEDIDFile, &params);
+  }
+
+  // Fallback to command line if the file doesn't exit or failed to read.
+  if (success || CreateSnapshotFromCommandLine(&params)) {
+    DCHECK_NE(DISPLAY_CONNECTION_TYPE_NONE, params.type);
     displays_.push_back(new DriDisplaySnapshotProxy(params, display_manager_));
     has_dummy_display_ = true;
   }
 }
 
 void NativeDisplayDelegateProxy::GrabServer() {
 }
 
 void NativeDisplayDelegateProxy::UngrabServer() {
 }
@@ skipping 170 matching lines @@
 void NativeDisplayDelegateProxy::OnDisplayConfigured(int64_t display_id,
                                                      bool status) {
   auto it = configure_callback_map_.find(display_id);
   if (it != configure_callback_map_.end()) {
     it->second.Run(status);
     configure_callback_map_.erase(it);
   }
 }
 
 }  // namespace ui