Refactor MediaStreamManager to never output real device id. It now always output sourceId in the fo…

content/browser/renderer_host/media/media_source_id_factory.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/browser/renderer_host/media/media_source_id_factory.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "crypto/hmac.h"
+
+namespace content {
+
+bool MediaSourceIdFactory::DoesSourceIdMatchDeviceId(
+    const GURL& security_origin,
+    const std::string& source_id,
+    const std::string& device_id) {
+  crypto::HMAC hmac(crypto::HMAC::SHA256);
+  bool result = hmac.Init(security_origin.spec());
+  DCHECK(result);
+  std::vector<uint8> converted_guid;
+  if (!base::HexStringToBytes(source_id, &converted_guid))
+    return false;
+  return hmac.Verify(
+      device_id,
+      base::StringPiece(reinterpret_cast<const char*>(&converted_guid[0]),
+                        converted_guid.size()));
+}
+
+void MediaSourceIdFactory::GenerateSourceId(const GURL& origin,
+                                           const std::string& device_id,
+                                           std::string* source_id) {
+  // TODO(perkj): Add a random salt to this HMAC that is dependent on current
+  // user profile. This salt should be regenerated if the cache is cleared.
+  crypto::HMAC hmac(crypto::HMAC::SHA256);
+  const size_t digest_length = hmac.DigestLength();
+  std::vector<uint8> digest(digest_length);
+  bool result = hmac.Init(origin.spec()) &&
+                hmac.Sign(device_id, &digest[0], digest.size());
+  CHECK(result);
+
+  *source_id = StringToLowerASCII(base::HexEncode(&digest[0], digest.size()));
+}
+
+void MediaSourceIdFactory::GenerateSourceIds(
+    const GURL& origin,
+    const StreamDeviceInfoArray& raw_devices,
+    StreamDeviceInfoArray* devices_with_sourceid) {
+  DCHECK(devices_with_sourceid);
+
+  // Replace raw ids with hmac'd ids.
+  for (StreamDeviceInfoArray::const_iterator device_itr = raw_devices.begin();
+       device_itr != raw_devices.end();
+       ++device_itr) {
+    StreamDeviceInfo current_device_info = *device_itr;
+    GenerateSourceId(origin,
+                     device_itr->device.id,
+                     &current_device_info.device.id);
+    devices_with_sourceid->push_back(current_device_info);
+  }
+}
+
+}  // namespace content