Mojo C++ bindings: make ipc/ mojom targets to use STL string/vector types

mojo/public/cpp/bindings/array_traits_stl.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_STL_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_STL_H_
 
 #include <vector>
 
 #include "mojo/public/cpp/bindings/array_traits.h"
@@ skipping 24 matching lines @@
                                                   size_t index) {
     return input[index];
   }
 
   static typename std::vector<T>::const_reference GetAt(
       const std::vector<T>& input,
       size_t index) {
     return input[index];
   }
 
-  static bool Resize(std::vector<T>& input, size_t size) {
+  static inline bool Resize(std::vector<T>& input, size_t size) {
+    // Instead of calling std::vector<T>::resize() directly, this is a hack to
+    // make compilers happy. Some compilers (e.g., Mac, Android, Linux MSan)
+    // currently don't allow resizing types like
+    // std::vector<std::vector<MoveOnlyType>>.
+    // Because the deserialization code doesn't care about the original contents
+    // of |input|, we discard them directly.
+    //
+    // The "inline" keyword of this method matters. Without it, we have observed
+    // significant perf regression with some tests on Mac. crbug.com/631415
     if (input.size() != size) {
-      // This is a hack to make compilers for Mac and Android happy. They
-      // currently don't allow resizing types like
-      // std::vector<std::vector<MoveOnlyType>>.
-      // Because the deserialization code doesn't care about the original
-      // contents of |input|, we discard them directly.
       std::vector<T> temp(size);
       input.swap(temp);
     }
 
     return true;
   }
 };
 
 // This ArrayTraits specialization is used only for serialization.
 template <typename T>
@@ skipping 15 matching lines @@
     ++iterator;
   }
   static const T& GetValue(ConstIterator& iterator) {
     return *iterator;
   }
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_ARRAY_TRAITS_STL_H_