Add UTF16ToUTF8AndAdjustOffset() to base/.

base/utf_offset_string_conversions_unittest.cc

 // Copyright (c) 2011 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.
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/string_piece.h"
 #include "base/utf_offset_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 18 matching lines @@
     {"\xed\xb0\x80z", 3, 1},
     {"A\xF0\x90\x8C\x80z", 1, 1},
     {"A\xF0\x90\x8C\x80z", 2, kNpos},
     {"A\xF0\x90\x8C\x80z", 5, 3},
   };
   for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf8_to_utf16_cases); ++i) {
     size_t offset = utf8_to_utf16_cases[i].input_offset;
     UTF8ToUTF16AndAdjustOffset(utf8_to_utf16_cases[i].utf8, &offset);
     EXPECT_EQ(utf8_to_utf16_cases[i].output_offset, offset);
   }
+
+  struct UTF16ToUTF8Case {
+    char16 utf16[10];
+    size_t input_offset;
+    size_t output_offset;
+  } utf16_to_utf8_cases[] = {
+      {{}, 0, kNpos},
+      // Converted to 3-byte utf-8 sequences
+      {{0x5909, 0x63DB}, 2, kNpos},
+      {{0x5909, 0x63DB}, 1, 3},
+      // Converted to 2-byte utf-8 sequences
+      {{'A', 0x00bc, 0x00be, 'z'}, 1, 1},
+      {{'A', 0x00bc, 0x00be, 'z'}, 2, 3},
+      {{'A', 0x00bc, 0x00be, 'z'}, 3, 5},
+      // Surrogate pair
+      {{'A', 0xd800, 0xdf00, 'z'}, 1, 1},
+      {{'A', 0xd800, 0xdf00, 'z'}, 2, kNpos},
+      {{'A', 0xd800, 0xdf00, 'z'}, 3, 5},
+  };
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf16_to_utf8_cases); ++i) {
+    size_t offset = utf16_to_utf8_cases[i].input_offset;
+    UTF16ToUTF8AndAdjustOffset(utf16_to_utf8_cases[i].utf16, &offset);
+    EXPECT_EQ(utf16_to_utf8_cases[i].output_offset, offset);
+  }
 }
 
 TEST(UTFOffsetStringConversionsTest, LimitOffsets) {
   const size_t kLimit = 10;
   const size_t kItems = 20;
   std::vector<size_t> size_ts;
   for (size_t t = 0; t < kItems; ++t)
     size_ts.push_back(t);
   std::for_each(size_ts.begin(), size_ts.end(),
                 LimitOffset<string16>(kLimit));
@@ skipping 72 matching lines @@
     }
     size_t expected_3[] = {kNpos, kNpos, kNpos, 0, 1, kNpos, kNpos, kNpos, 5, 6,
                            7, 8, kNpos, kNpos, 11, kNpos, kNpos};
     EXPECT_EQ(offsets.size(), arraysize(expected_3));
     for (size_t i = 0; i < arraysize(expected_3); ++i)
       EXPECT_EQ(expected_3[i], offsets[i]);
   }
 }
 
 }  // namaspace base