[CrOS Tether] Add a static TruncateDeviceIdForLogs() function.

BUG=672263

Review-Url: https://codereview.chromium.org/2590713002
Cr-Commit-Position: refs/heads/master@{#439730}

components/cryptauth/remote_device.cc

@@ -30,28 +30,34 @@ RemoteDevice::RemoteDevice(const RemoteDevice& other) = default;
 RemoteDevice::~RemoteDevice() {}
 
 std::string RemoteDevice::GetDeviceId() const {
-   std::string to_return;
-   base::Base64Encode(public_key, &to_return);
-   return to_return;
+  std::string to_return;
+  base::Base64Encode(public_key, &to_return);
+  return to_return;
 }
 
 std::string RemoteDevice::GetTruncatedDeviceIdForLogs() const {
-   std::string id = GetDeviceId();
-   if (id.length() <= 10) {
-      return id;
-   }
-
-   return id.substr(0, 5) + "..." + id.substr(id.length() - 5, id.length());
+  return RemoteDevice::TruncateDeviceIdForLogs(GetDeviceId());
 }
 
 bool RemoteDevice::operator==(const RemoteDevice& other) const {
-   return user_id == other.user_id
-         && name == other.name
-         && public_key == other.public_key
-         && bluetooth_type == other.bluetooth_type
-         && bluetooth_address == other.bluetooth_address
-         && persistent_symmetric_key == other.persistent_symmetric_key
-         && sign_in_challenge == other.sign_in_challenge;
+  return user_id == other.user_id
+      && name == other.name
+      && public_key == other.public_key
+      && bluetooth_type == other.bluetooth_type
+      && bluetooth_address == other.bluetooth_address
+      && persistent_symmetric_key == other.persistent_symmetric_key
+      && sign_in_challenge == other.sign_in_challenge;
+}
+
+// static
+std::string RemoteDevice::TruncateDeviceIdForLogs(const std::string& full_id) {
+  if (full_id.length() <= 10) {
+    return full_id;
+  }
+
+  return full_id.substr(0, 5)
+      + "..."
+      + full_id.substr(full_id.length() - 5, full_id.length());
 }
 
 }  // namespace cryptauth

components/cryptauth/remote_device.h

@@ -42,6 +42,9 @@ struct RemoteDevice {
   std::string GetTruncatedDeviceIdForLogs() const;
 
   bool operator==(const RemoteDevice& other) const;
+
+  // Static method for truncated device ID for logs.
+  static std::string TruncateDeviceIdForLogs(const std::string& full_id);
 };
 
 typedef std::vector<RemoteDevice> RemoteDeviceList;