Make ValueCounter::Entry non-copyable and move-able

This CL also makes its member to be stack allocated base::Value
instead of dynamic allocated one.

Bug: None
Test: Minor cleanup, no behavior changes expected.
Change-Id: I6b97497c43e7c37b6dd5481049834c3b54b9b1a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2133207
Commit-Queue: Istiaque Ahmed <lazyboy@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756056}

extensions/common/value_counter.cc

@@ -13,10 +13,15 @@
 namespace extensions {
 
 struct ValueCounter::Entry {
-  explicit Entry(std::unique_ptr<base::Value> value)
-      : value(std::move(value)), count(1) {}
+  explicit Entry(base::Value value) : value(std::move(value)), count(1) {}
 
-  std::unique_ptr<base::Value> value;
+  Entry(Entry&) = delete;
+  Entry& operator=(Entry&) = delete;
+
+  Entry(Entry&&) = default;
+  Entry& operator=(Entry&&) = default;
+
+  base::Value value;
   int count;
 };
 
@@ -27,20 +32,20 @@ ValueCounter::~ValueCounter() {
 }
 
 bool ValueCounter::Add(const base::Value& value) {
-  for (const auto& entry : entries_) {
-    if (entry->value->Equals(&value)) {
-      ++entry->count;
+  for (auto& entry : entries_) {
+    if (entry.value.Equals(&value)) {
+      ++entry.count;
       return false;
     }
   }
-  entries_.push_back(std::make_unique<Entry>(value.CreateDeepCopy()));
+  entries_.emplace_back(value.Clone());
   return true;
 }
 
 bool ValueCounter::Remove(const base::Value& value) {
   for (auto it = entries_.begin(); it != entries_.end(); ++it) {
-    if ((*it)->value->Equals(&value)) {
-      if (--(*it)->count == 0) {
+    if (it->value.Equals(&value)) {
+      if (--it->count == 0) {
         std::swap(*it, entries_.back());
         entries_.pop_back();
         return true;  // Removed the last entry.

extensions/common/value_counter.h

@@ -5,7 +5,6 @@
 #ifndef EXTENSIONS_COMMON_VALUE_COUNTER_H_
 #define EXTENSIONS_COMMON_VALUE_COUNTER_H_
 
-#include <memory>
 #include <vector>
 
 #include "base/macros.h"
@@ -42,7 +41,7 @@ class ValueCounter {
 
  private:
   struct Entry;
-  std::vector<std::unique_ptr<Entry>> entries_;
+  std::vector<Entry> entries_;
 
   DISALLOW_COPY_AND_ASSIGN(ValueCounter);
 };