Allow embedders to share code to override UI strings.

components/variations/service/ui_string_overrider.h

+// Copyright 2015 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 COMPONENTS_VARIATIONS_SERVICE_UI_STRING_OVERRIDER_H_
+#define COMPONENTS_VARIATIONS_SERVICE_UI_STRING_OVERRIDER_H_
+
+#include "base/basictypes.h"
+#include "base/macros.h"
+#include "base/strings/string16.h"
+
+namespace variations {
+
+// Provides a mapping from hashes of generated resource names to their IDs. The
+// mapping is provided by the embedder as two arrays |resource_hashes|, a sorted
+// array of resource name hashes, and |resource_indices| an array of resource
+// indices in the same order.
+//
+// The mapping is created by generate_resources_map.py based on generated
+// resources header files. The script ensure that if one header file contains
+// |#define IDS_FOO 12345| then for some index |i|, |resource_hashes[i]| will
+// be equal to |HASH("IDS_FOO")| and |resource_indices[i]| will be equal to
+// |12345|.
+//
+// Both array must have the same length |num_resources|. They are not owned by
+// the UIStringOverrider and the embedder is responsible for their lifetime
+// (usually by passing pointer to static data).
+//
+// This class is copy-constructible by design as it does not owns the array
+// and only have reference to globally allocated constants.
+class UIStringOverrider {
+ public:
+  UIStringOverrider();
+  UIStringOverrider(const uint32_t* resource_hashes,
+                    const int* resource_indices,
+                    size_t num_resources);
+  ~UIStringOverrider();
+
+  // Returns the resource index corresponding to the given hash or -1 if no
+  // resources is found. Visible for testing.
+  int GetResourceIndex(uint32_t hash);
+
+  // Overrides the string resource specified by |hash| with |string| in the
+  // resource bundle.
+  void OverrideUIString(uint32_t hash, const base::string16& string);
+
+ private:
+  const uint32_t* const resource_hashes_;
+  const int* const resource_indices_;
+  size_t const num_resources_;
+
+  DISALLOW_ASSIGN(UIStringOverrider);
+};
+
+}  // namespace variations
+
+#endif  // COMPONENTS_VARIATIONS_SERVICE_UI_STRING_OVERRIDER_H_