Factor out authorization from AudioRendererHost.

content/public/browser/media_device_id.cc

 // Copyright 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 "content/public/browser/media_device_id.h"
 
+#include "base/strings/string_util.h"
 #include "content/browser/browser_main_loop.h"
 #include "content/browser/renderer_host/media/media_stream_manager.h"
+#include "media/audio/audio_device_description.h"
 
 namespace content {
 
 std::string GetHMACForMediaDeviceID(const std::string& salt,
                                     const url::Origin& security_origin,
                                     const std::string& raw_unique_id) {
   return MediaStreamManager::GetHMACForMediaDeviceID(salt, security_origin,
                                                      raw_unique_id);
 }
 
@@ skipping 11 matching lines @@
                              const std::string& source_id,
                              std::string* device_id) {
   content::MediaStreamManager* manager =
       content::BrowserMainLoop::GetInstance()->media_stream_manager();
 
   return manager->TranslateSourceIdToDeviceId(
       content::MEDIA_DEVICE_VIDEO_CAPTURE, salt, security_origin, source_id,
       device_id);
 }
 
+bool IsValidDeviceId(const std::string& device_id) {
+  constexpr int hash_size = 64;  // 32 bytes * 2 char/byte hex encoding
+  if (media::AudioDeviceDescription::IsDefaultDevice(device_id) ||
+      device_id == media::AudioDeviceDescription::kCommunicationsDeviceId)
+    return true;
+
+  if (device_id.length() != hash_size)
+    return false;
+
+  return std::all_of(device_id.cbegin(), device_id.cend(), [](const char& c) {
+    return base::IsAsciiLower(c) || base::IsAsciiDigit(c);
+  });
+}
+
 }  // namespace content