Make Quick Unlock API code more compact.

Use more C++ and base/ features to simplify the code. Fix all the nits
and lint errors as well.

Change-Id: Ib3b80002bfd7b9df45ad535ddb94cdc086d0ca2f
Reviewed-on: https://chromium-review.googlesource.com/890239
Commit-Queue: Lei Zhang <thestig@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533151}

chrome/browser/chromeos/extensions/quick_unlock_private/quick_unlock_private_api.h

@@ -5,6 +5,9 @@
 #ifndef CHROME_BROWSER_CHROMEOS_EXTENSIONS_QUICK_UNLOCK_PRIVATE_QUICK_UNLOCK_PRIVATE_API_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_QUICK_UNLOCK_PRIVATE_QUICK_UNLOCK_PRIVATE_API_H_
 
+#include <memory>
+#include <vector>
+
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "chrome/browser/extensions/chrome_extension_function_details.h"