Bug 1480668 - Remove js::CStringHashPolicy. r=luke

It's identical to mozilla::CStringHasher.

Also fix a comment at the top of HashTable.h about CStringHasher.

--HG--
extra : rebase_source : 92176c4f6ea8041f309764b4ce0271a494853a7b

js/public/MemoryMetrics.h

@@ -123,13 +123,6 @@ struct InefficientNonFlatteningStringHashPolicy
     static bool match(const JSString* const& k, const Lookup& l);
 };
 
-struct CStringHashPolicy
-{
-    typedef const char* Lookup;
-    static HashNumber hash(const Lookup& l);
-    static bool match(const char* const& k, const Lookup& l);
-};
-
 // This file features many classes with numerous size_t fields, and each such
 // class has one or more methods that need to operate on all of these fields.
 // Writing these individually is error-prone -- it's easy to add a new field
@@ -604,7 +597,7 @@ struct RuntimeSizes
     GCSizes gc;
 
     typedef js::HashMap<const char*, ScriptSourceInfo,
-                        js::CStringHashPolicy,
+                        mozilla::CStringHasher,
                         js::SystemAllocPolicy> ScriptSourcesHashMap;
 
     // |allScriptSources| is only used transiently.  During the reporting phase
@@ -901,7 +894,7 @@ struct RealmStats
     void* extra;            // This field can be used by embedders.
 
     typedef js::HashMap<const char*, ClassInfo,
-                        js::CStringHashPolicy,
+                        mozilla::CStringHasher,
                         js::SystemAllocPolicy> ClassesHashMap;
 
     // These are similar to |allStrings| and |notableStrings| in ZoneStats.

js/src/vm/MemoryMetrics.cpp

@@ -122,18 +122,6 @@ InefficientNonFlatteningStringHashPolicy::match(const JSString* const& k, const
            : EqualStringsPure<char16_t, char16_t>(s1, l);
 }
 
-/* static */ HashNumber
-CStringHashPolicy::hash(const Lookup& l)
-{
-    return mozilla::HashString(l);
-}
-
-/* static */ bool
-CStringHashPolicy::match(const char* const& k, const Lookup& l)
-{
-    return strcmp(k, l) == 0;
-}
-
 } // namespace js
 
 namespace JS {

mfbt/HashTable.h

@@ -18,14 +18,14 @@
 //   conditions are true.
 //
 //   - The key type stored in the table (|Key| for |HashMap<Key, Value>|, |T|
-//     for |HashSet<T>|) is an integer, pointer, UniquePtr, float, double, or
-//     char*.
+//     for |HashSet<T>|) is an integer, pointer, UniquePtr, float, or double.
 //
 //   - The type used for lookups (|Lookup|) is the same as the key type. This
 //     is usually the case, but not always.
 //
-//   Otherwise, you must provide your own hash policy; see the "Hash Policy"
-//   section below.
+//   There is also a |CStringHasher| policy for |char*| keys. If your keys
+//   don't match any of the above cases, you must provide your own hash policy;
+//   see the "Hash Policy" section below.
 //
 // - AllocPolicy. This defines how allocations are done by the table.
 //