Convert pdf/ to use std::unique_ptr.

pdf/pdfium/pdfium_engine.cc

Index: pdf/pdfium/pdfium_engine.cc
diff --git a/pdf/pdfium/pdfium_engine.cc b/pdf/pdfium/pdfium_engine.cc
index 3899e0ee51eb3bf5278470fc2645cdee3e0e4752..0005adf9f030cf8be95cf77176c5a1a154c7de20 100644
--- a/pdf/pdfium/pdfium_engine.cc
+++ b/pdf/pdfium/pdfium_engine.cc
@@ -8,6 +8,7 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include <memory>
 #include <set>
 
 #include "base/i18n/icu_encoding_detection.h"
@@ -16,7 +17,6 @@
 #include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
 #include "base/numerics/safe_conversions.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ -2296,7 +2296,7 @@ std::string PDFiumEngine::GetPageAsJSON(int index) {
   if (index < 0 || static_cast<size_t>(index) > pages_.size() - 1)
     return "{}";
 
-  scoped_ptr<base::Value> node(
+  std::unique_ptr<base::Value> node(
       pages_[index]->GetAccessibleContentAsValue(current_rotation_));
   std::string page_json;
   base::JSONWriter::Write(*node, &page_json);