Update from https://crrev.com/327068

base/stl_util.h

Index: base/stl_util.h
diff --git a/base/stl_util.h b/base/stl_util.h
index 89a53b070ef515cf81d584098e7aace8ed2ba201..e937d2f3ed9157d433cc62fb71958bd9c71cd6d9 100644
--- a/base/stl_util.h
+++ b/base/stl_util.h
@@ -90,6 +90,14 @@ void STLDeleteContainerPairSecondPointers(ForwardIterator begin,
   }
 }
 
+// Counts the number of instances of val in a container.
+template <typename Container, typename T>
+typename std::iterator_traits<
+    typename Container::const_iterator>::difference_type
+STLCount(const Container& container, const T& val) {
+  return std::count(container.begin(), container.end(), val);
+}
+
 // To treat a possibly-empty vector as an array, use these functions.
 // If you know the array will never be empty, you can use &*v.begin()
 // directly, but that is undefined behaviour if |v| is empty.
@@ -195,6 +203,14 @@ bool ContainsKey(const Collection& collection, const Key& key) {
   return collection.find(key) != collection.end();
 }
 
+// Test to see if a collection like a vector contains a particular value.
+// Returns true if the value is in the collection.
+template <typename Collection, typename Value>
+bool ContainsValue(const Collection& collection, const Value& value) {
+  return std::find(collection.begin(), collection.end(), value) !=
+      collection.end();
+}
+
 namespace base {
 
 // Returns true if the container is sorted.