Split *AndAdjustOffset() functions into their own header, to restore utf_string_conversions.h to a simple, readable state.

BUG=4010
TEST=none
Review URL: http://codereview.chromium.org/387012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@31928 0039d316-1c4b-4281-b951-d872f2087c98

10 files changed, 505 insertions, 294 deletions

diff --git a/base/base.gyp b/base/base.gyp
index bcb88f6..b954e3b 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -332,6 +332,10 @@
         'tracked_objects.cc',
         'tracked_objects.h',
         'tuple.h',
+        'utf_offset_string_conversions.cc',
+        'utf_offset_string_conversions.h',
+        'utf_string_conversion_utils.cc',
+        'utf_string_conversion_utils.h',
         'utf_string_conversions.cc',
         'utf_string_conversions.h',
         'unix_domain_socket_posix.cc',
@@ -655,6 +659,7 @@
         'timer_unittest.cc',
         'tracked_objects_unittest.cc',
         'tuple_unittest.cc',
+        'utf_offset_string_conversions_unittest.cc',
         'utf_string_conversions_unittest.cc',
         'values_unittest.cc',
         'version_unittest.cc',
diff --git a/base/i18n/icu_string_conversions.h b/base/i18n/icu_string_conversions.h
index 7b0c77e..79d7e02 100644
--- a/base/i18n/icu_string_conversions.h
+++ b/base/i18n/icu_string_conversions.h
@@ -8,7 +8,6 @@
 #include <string>
 
 #include "base/string16.h"
-#include "base/string_piece.h"
 
 namespace base {
 
diff --git a/base/utf_offset_string_conversions.cc b/base/utf_offset_string_conversions.cc
new file mode 100644
index 0000000..69b572e
--- /dev/null
+++ b/base/utf_offset_string_conversions.cc
@@ -0,0 +1,122 @@
+// Copyright (c) 2009 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 "base/utf_offset_string_conversions.h"
+
+#include "base/string_piece.h"
+#include "base/utf_string_conversion_utils.h"
+
+using base::PrepareForUTF16Or32Output;
+using base::ReadUnicodeCharacter;
+using base::WriteUnicodeCharacter;
+
+// Generalized Unicode converter -----------------------------------------------
+
+// Converts the given source Unicode character type to the given destination
+// Unicode character type as a STL string. The given input buffer and size
+// determine the source, and the given output STL string will be replaced by
+// the result.
+template<typename SRC_CHAR>
+bool ConvertUnicode(const SRC_CHAR* src,
+                    size_t src_len,
+                    std::wstring* output,
+                    size_t* offset_for_adjustment) {
+  size_t output_offset =
+      (offset_for_adjustment && *offset_for_adjustment < src_len) ?
+          *offset_for_adjustment : std::wstring::npos;
+
+  // ICU requires 32-bit numbers.
+  bool success = true;
+  int32 src_len32 = static_cast<int32>(src_len);
+  for (int32 i = 0; i < src_len32; i++) {
+    uint32 code_point;
+    size_t original_i = i;
+    size_t chars_written = 0;
+    if (ReadUnicodeCharacter(src, src_len32, &i, &code_point)) {
+      chars_written = WriteUnicodeCharacter(code_point, output);
+    } else {
+      // TODO(jungshik): consider adding 'Replacement character' (U+FFFD)
+      // in place of an invalid codepoint.
+      success = false;
+    }
+    if ((output_offset != std::wstring::npos) &&
+        (*offset_for_adjustment > original_i)) {
+      // NOTE: ReadUnicodeCharacter() adjusts |i| to point _at_ the last
+      // character read, not after it (so that incrementing it in the loop
+      // increment will place it at the right location), so we need to account
+      // for that in determining the amount that was read.
+      if (*offset_for_adjustment <= static_cast<size_t>(i))
+        output_offset = std::wstring::npos;
+      else
+        output_offset += chars_written - (i - original_i + 1);
+    }
+  }
+
+  if (offset_for_adjustment)
+    *offset_for_adjustment = output_offset;
+  return success;
+}
+
+// UTF-8 <-> Wide --------------------------------------------------------------
+
+bool UTF8ToWideAndAdjustOffset(const char* src,
+                               size_t src_len,
+                               std::wstring* output,
+                               size_t* offset_for_adjustment) {
+  PrepareForUTF16Or32Output(src, src_len, output);
+  return ConvertUnicode(src, src_len, output, offset_for_adjustment);
+}
+
+std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
+                                       size_t* offset_for_adjustment) {
+  std::wstring ret;
+  UTF8ToWideAndAdjustOffset(utf8.data(), utf8.length(), &ret,
+                            offset_for_adjustment);
+  return ret;
+}
+
+// UTF-16 <-> Wide -------------------------------------------------------------
+
+#if defined(WCHAR_T_IS_UTF16)
+
+// When wide == UTF-16, then conversions are a NOP.
+bool UTF16ToWideAndAdjustOffset(const char16* src,
+                                size_t src_len,
+                                std::wstring* output,
+                                size_t* offset_for_adjustment) {
+  output->assign(src, src_len);
+  if (offset_for_adjustment && (*offset_for_adjustment >= src_len))
+    *offset_for_adjustment = std::wstring::npos;
+  return true;
+}
+
+std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
+                                        size_t* offset_for_adjustment) {
+  if (offset_for_adjustment && (*offset_for_adjustment >= utf16.length()))
+    *offset_for_adjustment = std::wstring::npos;
+  return utf16;
+}
+
+#elif defined(WCHAR_T_IS_UTF32)
+
+bool UTF16ToWideAndAdjustOffset(const char16* src,
+                                size_t src_len,
+                                std::wstring* output,
+                                size_t* offset_for_adjustment) {
+  output->clear();
+  // Assume that normally we won't have any non-BMP characters so the counts
+  // will be the same.
+  output->reserve(src_len);
+  return ConvertUnicode(src, src_len, output, offset_for_adjustment);
+}
+
+std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
+                                        size_t* offset_for_adjustment) {
+  std::wstring ret;
+  UTF16ToWideAndAdjustOffset(utf16.data(), utf16.length(), &ret,
+                             offset_for_adjustment);
+  return ret;
+}
+
+#endif  // defined(WCHAR_T_IS_UTF32)
diff --git a/base/utf_offset_string_conversions.h b/base/utf_offset_string_conversions.h
new file mode 100644
index 0000000..0a1a682
--- /dev/null
+++ b/base/utf_offset_string_conversions.h
@@ -0,0 +1,35 @@
+// Copyright (c) 2009 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 BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
+#define BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
+
+#include <string>
+
+#include "base/string16.h"
+
+namespace base {
+class StringPiece;
+}
+
+// Like the conversions in utf_string_conversions.h, but also take offsets into
+// the source strings, which will be adjusted to point at the same logical place
+// in the result strings.  If this isn't possible because the offsets point past
+// the end of the source strings or into the middle of multibyte sequences, they
+// will be set to std::wstring::npos.  |offset_for_adjustment| may be NULL.
+bool UTF8ToWideAndAdjustOffset(const char* src,
+                               size_t src_len,
+                               std::wstring* output,
+                               size_t* offset_for_adjustment);
+std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
+                                       size_t* offset_for_adjustment);
+
+bool UTF16ToWideAndAdjustOffset(const char16* src,
+                                size_t src_len,
+                                std::wstring* output,
+                                size_t* offset_for_adjustment);
+std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
+                                        size_t* offset_for_adjustment);
+
+#endif  // BASE_UTF_OFFSET_STRING_CONVERSIONS_H_
diff --git a/base/utf_offset_string_conversions_unittest.cc b/base/utf_offset_string_conversions_unittest.cc
new file mode 100644
index 0000000..00d87d3
--- /dev/null
+++ b/base/utf_offset_string_conversions_unittest.cc
@@ -0,0 +1,80 @@
+// Copyright (c) 2009 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 "base/logging.h"
+#include "base/string_piece.h"
+#include "base/utf_offset_string_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+// Given a null-terminated string of wchar_t with each wchar_t representing
+// a UTF-16 code unit, returns a string16 made up of wchar_t's in the input.
+// Each wchar_t should be <= 0xFFFF and a non-BMP character (> U+FFFF)
+// should be represented as a surrogate pair (two UTF-16 units)
+// *even* where wchar_t is 32-bit (Linux and Mac).
+//
+// This is to help write tests for functions with string16 params until
+// the C++ 0x UTF-16 literal is well-supported by compilers.
+string16 BuildString16(const wchar_t* s) {
+#if defined(WCHAR_T_IS_UTF16)
+  return string16(s);
+#elif defined(WCHAR_T_IS_UTF32)
+  string16 u16;
+  while (*s != 0) {
+    DCHECK(static_cast<unsigned int>(*s) <= 0xFFFFu);
+    u16.push_back(*s++);
+  }
+  return u16;
+#endif
+}
+
+}  // namespace
+
+TEST(UTFOffsetStringConversionsTest, AdjustOffset) {
+  struct UTF8ToWideCase {
+    const char* utf8;
+    size_t input_offset;
+    size_t output_offset;
+  } utf8_to_wide_cases[] = {
+    {"", 0, std::wstring::npos},
+    {"\xe4\xbd\xa0\xe5\xa5\xbd", 1, std::wstring::npos},
+    {"\xe4\xbd\xa0\xe5\xa5\xbd", 3, 1},
+    {"\xed\xb0\x80z", 3, 0},
+    {"A\xF0\x90\x8C\x80z", 1, 1},
+    {"A\xF0\x90\x8C\x80z", 2, std::wstring::npos},
+#if defined(WCHAR_T_IS_UTF16)
+    {"A\xF0\x90\x8C\x80z", 5, 3},
+#elif defined(WCHAR_T_IS_UTF32)
+    {"A\xF0\x90\x8C\x80z", 5, 2},
+#endif
+  };
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf8_to_wide_cases); ++i) {
+    size_t offset = utf8_to_wide_cases[i].input_offset;
+    UTF8ToWideAndAdjustOffset(utf8_to_wide_cases[i].utf8, &offset);
+    EXPECT_EQ(utf8_to_wide_cases[i].output_offset, offset);
+  }
+
+#if defined(WCHAR_T_IS_UTF32)
+  struct UTF16ToWideCase {
+    const wchar_t* wide;
+    size_t input_offset;
+    size_t output_offset;
+  } utf16_to_wide_cases[] = {
+    {L"\xD840\xDC00\x4E00", 0, 0},
+    {L"\xD840\xDC00\x4E00", 1, std::wstring::npos},
+    {L"\xD840\xDC00\x4E00", 2, 1},
+  };
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf16_to_wide_cases); ++i) {
+    size_t offset = utf16_to_wide_cases[i].input_offset;
+    UTF16ToWideAndAdjustOffset(BuildString16(utf16_to_wide_cases[i].wide),
+                               &offset);
+    EXPECT_EQ(utf16_to_wide_cases[i].output_offset, offset);
+  }
+#endif
+}
+
+}  // namaspace base
diff --git a/base/utf_string_conversion_utils.cc b/base/utf_string_conversion_utils.cc
new file mode 100644
index 0000000..ebd8fd9
--- /dev/null
+++ b/base/utf_string_conversion_utils.cc
@@ -0,0 +1,148 @@
+// Copyright (c) 2009 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 "base/utf_string_conversion_utils.h"
+
+#include "base/third_party/icu/icu_utf.h"
+
+namespace base {
+
+// ReadUnicodeCharacter --------------------------------------------------------
+
+bool ReadUnicodeCharacter(const char* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point_out) {
+  // U8_NEXT expects to be able to use -1 to signal an error, so we must
+  // use a signed type for code_point.  But this function returns false
+  // on error anyway, so code_point_out is unsigned.
+  int32 code_point;
+  CBU8_NEXT(src, *char_index, src_len, code_point);
+  *code_point_out = static_cast<uint32>(code_point);
+
+  // The ICU macro above moves to the next char, we want to point to the last
+  // char consumed.
+  (*char_index)--;
+
+  // Validate the decoded value.
+  return IsValidCodepoint(code_point);
+}
+
+bool ReadUnicodeCharacter(const char16* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point) {
+  if (CBU16_IS_SURROGATE(src[*char_index])) {
+    if (!CBU16_IS_SURROGATE_LEAD(src[*char_index]) ||
+        *char_index + 1 >= src_len ||
+        !CBU16_IS_TRAIL(src[*char_index + 1])) {
+      // Invalid surrogate pair.
+      return false;
+    }
+
+    // Valid surrogate pair.
+    *code_point = CBU16_GET_SUPPLEMENTARY(src[*char_index],
+                                          src[*char_index + 1]);
+    (*char_index)++;
+  } else {
+    // Not a surrogate, just one 16-bit word.
+    *code_point = src[*char_index];
+  }
+
+  return IsValidCodepoint(*code_point);
+}
+
+#if defined(WCHAR_T_IS_UTF32)
+bool ReadUnicodeCharacter(const wchar_t* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point) {
+  // Conversion is easy since the source is 32-bit.
+  *code_point = src[*char_index];
+
+  // Validate the value.
+  return IsValidCodepoint(*code_point);
+}
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// WriteUnicodeCharacter -------------------------------------------------------
+
+size_t WriteUnicodeCharacter(uint32 code_point, std::string* output) {
+  if (code_point <= 0x7f) {
+    // Fast path the common case of one byte.
+    output->push_back(code_point);
+    return 1;
+  }
+
+
+  // CBU8_APPEND_UNSAFE can append up to 4 bytes.
+  size_t char_offset = output->length();
+  size_t original_char_offset = char_offset;
+  output->resize(char_offset + CBU8_MAX_LENGTH);
+
+  CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+
+  // CBU8_APPEND_UNSAFE will advance our pointer past the inserted character, so
+  // it will represent the new length of the string.
+  output->resize(char_offset);
+  return char_offset - original_char_offset;
+}
+
+size_t WriteUnicodeCharacter(uint32 code_point, string16* output) {
+  if (CBU16_LENGTH(code_point) == 1) {
+    // Thie code point is in the Basic Multilingual Plane (BMP).
+    output->push_back(static_cast<char16>(code_point));
+    return 1;
+  }
+  // Non-BMP characters use a double-character encoding.
+  size_t char_offset = output->length();
+  output->resize(char_offset + CBU16_MAX_LENGTH);
+  CBU16_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
+  return CBU16_MAX_LENGTH;
+}
+
+// Generalized Unicode converter -----------------------------------------------
+
+template<typename CHAR>
+void PrepareForUTF8Output(const CHAR* src,
+                          size_t src_len,
+                          std::string* output) {
+  output->clear();
+  if (src_len == 0)
+    return;
+  if (src[0] < 0x80) {
+    // Assume that the entire input will be ASCII.
+    output->reserve(src_len);
+  } else {
+    // Assume that the entire input is non-ASCII and will have 3 bytes per char.
+    output->reserve(src_len * 3);
+  }
+}
+
+// Instantiate versions we know callers will need.
+template void PrepareForUTF8Output(const wchar_t*, size_t, std::string*);
+template void PrepareForUTF8Output(const char16*, size_t, std::string*);
+
+template<typename STRING>
+void PrepareForUTF16Or32Output(const char* src,
+                               size_t src_len,
+                               STRING* output) {
+  output->clear();
+  if (src_len == 0)
+    return;
+  if (static_cast<unsigned char>(src[0]) < 0x80) {
+    // Assume the input is all ASCII, which means 1:1 correspondence.
+    output->reserve(src_len);
+  } else {
+    // Otherwise assume that the UTF-8 sequences will have 2 bytes for each
+    // character.
+    output->reserve(src_len / 2);
+  }
+}
+
+// Instantiate versions we know callers will need.
+template void PrepareForUTF16Or32Output(const char*, size_t, std::wstring*);
+template void PrepareForUTF16Or32Output(const char*, size_t, string16*);
+
+}  // namespace base
diff --git a/base/utf_string_conversion_utils.h b/base/utf_string_conversion_utils.h
new file mode 100644
index 0000000..a8a76c5
--- /dev/null
+++ b/base/utf_string_conversion_utils.h
@@ -0,0 +1,86 @@
+// Copyright (c) 2009 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 BASE_UTF_STRING_CONVERSION_UTILS_H_
+#define BASE_UTF_STRING_CONVERSION_UTILS_H_
+
+// This should only be used by the various UTF string conversion files.
+
+#include "base/string16.h"
+
+namespace base {
+
+inline bool IsValidCodepoint(uint32 code_point) {
+  // Excludes the surrogate code points ([0xD800, 0xDFFF]) and
+  // codepoints larger than 0x10FFFF (the highest codepoint allowed).
+  // Non-characters and unassigned codepoints are allowed.
+  return code_point < 0xD800u ||
+         (code_point >= 0xE000u && code_point <= 0x10FFFFu);
+}
+
+// ReadUnicodeCharacter --------------------------------------------------------
+
+// Reads a UTF-8 stream, placing the next code point into the given output
+// |*code_point|. |src| represents the entire string to read, and |*char_index|
+// is the character offset within the string to start reading at. |*char_index|
+// will be updated to index the last character read, such that incrementing it
+// (as in a for loop) will take the reader to the next character.
+//
+// Returns true on success. On false, |*code_point| will be invalid.
+bool ReadUnicodeCharacter(const char* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point_out);
+
+// Reads a UTF-16 character. The usage is the same as the 8-bit version above.
+bool ReadUnicodeCharacter(const char16* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point);
+
+#if defined(WCHAR_T_IS_UTF32)
+// Reads UTF-32 character. The usage is the same as the 8-bit version above.
+bool ReadUnicodeCharacter(const wchar_t* src,
+                          int32 src_len,
+                          int32* char_index,
+                          uint32* code_point);
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// WriteUnicodeCharacter -------------------------------------------------------
+
+// Appends a UTF-8 character to the given 8-bit string.  Returns the number of
+// bytes written.
+size_t WriteUnicodeCharacter(uint32 code_point, std::string* output);
+
+// Appends the given code point as a UTF-16 character to the given 16-bit
+// string.  Returns the number of 16-bit values written.
+size_t WriteUnicodeCharacter(uint32 code_point, string16* output);
+
+#if defined(WCHAR_T_IS_UTF32)
+// Appends the given UTF-32 character to the given 32-bit string.  Returns the
+// number of 32-bit values written.
+inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
+  // This is the easy case, just append the character.
+  output->push_back(code_point);
+  return 1;
+}
+#endif  // defined(WCHAR_T_IS_UTF32)
+
+// Generalized Unicode converter -----------------------------------------------
+
+// Guesses the length of the output in UTF-8 in bytes, clears that output
+// string, and reserves that amount of space.  We assume that the input
+// character types are unsigned, which will be true for UTF-16 and -32 on our
+// systems.
+template<typename CHAR>
+void PrepareForUTF8Output(const CHAR* src, size_t src_len, std::string* output);
+
+// Prepares an output buffer (containing either UTF-16 or -32 data) given some
+// UTF-8 input that will be converted to it.  See PrepareForUTF8Output().
+template<typename STRING>
+void PrepareForUTF16Or32Output(const char* src, size_t src_len, STRING* output);
+
+}  // namespace base
+
+#endif  // BASE_UTF_STRING_CONVERSION_UTILS_H_
diff --git a/base/utf_string_conversions.cc b/base/utf_string_conversions.cc
index ee52f47..7376933 100644
--- a/base/utf_string_conversions.cc
+++ b/base/utf_string_conversions.cc
@@ -4,133 +4,16 @@
 
 #include "base/utf_string_conversions.h"
 
-#include <vector>
+#include "base/string_piece.h"
+#include "base/utf_string_conversion_utils.h"
 
-#include "base/basictypes.h"
-#include "base/logging.h"
-#include "base/string_util.h"
-#include "base/third_party/icu/icu_utf.h"
+using base::PrepareForUTF8Output;
+using base::PrepareForUTF16Or32Output;
+using base::ReadUnicodeCharacter;
+using base::WriteUnicodeCharacter;
 
 namespace {
 
-inline bool IsValidCodepoint(uint32 code_point) {
-  // Excludes the surrogate code points ([0xD800, 0xDFFF]) and
-  // codepoints larger than 0x10FFFF (the highest codepoint allowed).
-  // Non-characters and unassigned codepoints are allowed.
-  return code_point < 0xD800u ||
-         (code_point >= 0xE000u && code_point <= 0x10FFFFu);
-}
-
-// ReadUnicodeCharacter --------------------------------------------------------
-
-// Reads a UTF-8 stream, placing the next code point into the given output
-// |*code_point|. |src| represents the entire string to read, and |*char_index|
-// is the character offset within the string to start reading at. |*char_index|
-// will be updated to index the last character read, such that incrementing it
-// (as in a for loop) will take the reader to the next character.
-//
-// Returns true on success. On false, |*code_point| will be invalid.
-bool ReadUnicodeCharacter(const char* src, int32 src_len,
-                          int32* char_index, uint32* code_point_out) {
-  // U8_NEXT expects to be able to use -1 to signal an error, so we must
-  // use a signed type for code_point.  But this function returns false
-  // on error anyway, so code_point_out is unsigned.
-  int32 code_point;
-  CBU8_NEXT(src, *char_index, src_len, code_point);
-  *code_point_out = static_cast<uint32>(code_point);
-
-  // The ICU macro above moves to the next char, we want to point to the last
-  // char consumed.
-  (*char_index)--;
-
-  // Validate the decoded value.
-  return IsValidCodepoint(code_point);
-}
-
-// Reads a UTF-16 character. The usage is the same as the 8-bit version above.
-bool ReadUnicodeCharacter(const char16* src, int32 src_len,
-                          int32* char_index, uint32* code_point) {
-  if (CBU16_IS_SURROGATE(src[*char_index])) {
-    if (!CBU16_IS_SURROGATE_LEAD(src[*char_index]) ||
-        *char_index + 1 >= src_len ||
-        !CBU16_IS_TRAIL(src[*char_index + 1])) {
-      // Invalid surrogate pair.
-      return false;
-    }
-
-    // Valid surrogate pair.
-    *code_point = CBU16_GET_SUPPLEMENTARY(src[*char_index],
-                                          src[*char_index + 1]);
-    (*char_index)++;
-  } else {
-    // Not a surrogate, just one 16-bit word.
-    *code_point = src[*char_index];
-  }
-
-  return IsValidCodepoint(*code_point);
-}
-
-#if defined(WCHAR_T_IS_UTF32)
-// Reads UTF-32 character. The usage is the same as the 8-bit version above.
-bool ReadUnicodeCharacter(const wchar_t* src, int32 src_len,
-                          int32* char_index, uint32* code_point) {
-  // Conversion is easy since the source is 32-bit.
-  *code_point = src[*char_index];
-
-  // Validate the value.
-  return IsValidCodepoint(*code_point);
-}
-#endif  // defined(WCHAR_T_IS_UTF32)
-
-// WriteUnicodeCharacter -------------------------------------------------------
-
-// Appends a UTF-8 character to the given 8-bit string.  Returns the number of
-// bytes written.
-size_t WriteUnicodeCharacter(uint32 code_point, std::string* output) {
-  if (code_point <= 0x7f) {
-    // Fast path the common case of one byte.
-    output->push_back(code_point);
-    return 1;
-  }
-
-  // CBU8_APPEND_UNSAFE can append up to 4 bytes.
-  size_t char_offset = output->length();
-  size_t original_char_offset = char_offset;
-  output->resize(char_offset + CBU8_MAX_LENGTH);
-
-  CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
-
-  // CBU8_APPEND_UNSAFE will advance our pointer past the inserted character, so
-  // it will represent the new length of the string.
-  output->resize(char_offset);
-  return char_offset - original_char_offset;
-}
-
-// Appends the given code point as a UTF-16 character to the given 16-bit
-// string.  Returns the number of 16-bit values written.
-size_t WriteUnicodeCharacter(uint32 code_point, string16* output) {
-  if (CBU16_LENGTH(code_point) == 1) {
-    // Thie code point is in the Basic Multilingual Plane (BMP).
-    output->push_back(static_cast<char16>(code_point));
-    return 1;
-  }
-  // Non-BMP characters use a double-character encoding.
-  size_t char_offset = output->length();
-  output->resize(char_offset + CBU16_MAX_LENGTH);
-  CBU16_APPEND_UNSAFE(&(*output)[0], char_offset, code_point);
-  return CBU16_MAX_LENGTH;
-}
-
-#if defined(WCHAR_T_IS_UTF32)
-// Appends the given UTF-32 character to the given 32-bit string.  Returns the
-// number of 32-bit values written.
-inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
-  // This is the easy case, just append the character.
-  output->push_back(code_point);
-  return 1;
-}
-#endif  // defined(WCHAR_T_IS_UTF32)
-
 // Generalized Unicode converter -----------------------------------------------
 
 // Converts the given source Unicode character type to the given destination
@@ -140,90 +23,31 @@ inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
 template<typename SRC_CHAR, typename DEST_STRING>
 bool ConvertUnicode(const SRC_CHAR* src,
                     size_t src_len,
-                    DEST_STRING* output,
-                    size_t* offset_for_adjustment) {
-  size_t output_offset =
-      (offset_for_adjustment && *offset_for_adjustment < src_len) ?
-          *offset_for_adjustment : DEST_STRING::npos;
-
+                    DEST_STRING* output) {
   // ICU requires 32-bit numbers.
   bool success = true;
   int32 src_len32 = static_cast<int32>(src_len);
   for (int32 i = 0; i < src_len32; i++) {
     uint32 code_point;
-    size_t original_i = i;
-    size_t chars_written = 0;
     if (ReadUnicodeCharacter(src, src_len32, &i, &code_point)) {
-      chars_written = WriteUnicodeCharacter(code_point, output);
+      WriteUnicodeCharacter(code_point, output);
     } else {
       // TODO(jungshik): consider adding 'Replacement character' (U+FFFD)
       // in place of an invalid codepoint.
       success = false;
     }
-    if ((output_offset != DEST_STRING::npos) &&
-        (*offset_for_adjustment > original_i)) {
-      // NOTE: ReadUnicodeCharacter() adjusts |i| to point _at_ the last
-      // character read, not after it (so that incrementing it in the loop
-      // increment will place it at the right location), so we need to account
-      // for that in determining the amount that was read.
-      if (*offset_for_adjustment <= static_cast<size_t>(i))
-        output_offset = DEST_STRING::npos;
-      else
-        output_offset += chars_written - (i - original_i + 1);
-    }
   }
 
-  if (offset_for_adjustment)
-    *offset_for_adjustment = output_offset;
   return success;
 }
 
-// Guesses the length of the output in UTF-8 in bytes, clears that output
-// string, and reserves that amount of space.  We assume that the input
-// character types are unsigned, which will be true for UTF-16 and -32 on our
-// systems.
-template<typename CHAR>
-void PrepareForUTF8Output(const CHAR* src,
-                          size_t src_len,
-                          std::string* output) {
-  output->clear();
-  if (src_len == 0)
-    return;
-  if (src[0] < 0x80) {
-    // Assume that the entire input will be ASCII.
-    output->reserve(src_len);
-  } else {
-    // Assume that the entire input is non-ASCII and will have 3 bytes per char.
-    output->reserve(src_len * 3);
-  }
-}
-
-// Prepares an output buffer (containing either UTF-16 or -32 data) given some
-// UTF-8 input that will be converted to it.  See PrepareForUTF8Output().
-template<typename STRING>
-void PrepareForUTF16Or32Output(const char* src,
-                               size_t src_len,
-                               STRING* output) {
-  output->clear();
-  if (src_len == 0)
-    return;
-  if (static_cast<unsigned char>(src[0]) < 0x80) {
-    // Assume the input is all ASCII, which means 1:1 correspondence.
-    output->reserve(src_len);
-  } else {
-    // Otherwise assume that the UTF-8 sequences will have 2 bytes for each
-    // character.
-    output->reserve(src_len / 2);
-  }
-}
-
 }  // namespace
 
 // UTF-8 <-> Wide --------------------------------------------------------------
 
 bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output) {
   PrepareForUTF8Output(src, src_len, output);
-  return ConvertUnicode<wchar_t, std::string>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 std::string WideToUTF8(const std::wstring& wide) {
@@ -234,20 +58,14 @@ std::string WideToUTF8(const std::wstring& wide) {
   return ret;
 }
 
-bool UTF8ToWideAndAdjustOffset(const char* src,
-                               size_t src_len,
-                               std::wstring* output,
-                               size_t* offset_for_adjustment) {
+bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
   PrepareForUTF16Or32Output(src, src_len, output);
-  return ConvertUnicode<char, std::wstring>(src, src_len, output,
-                                            offset_for_adjustment);
+  return ConvertUnicode(src, src_len, output);
 }
 
-std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
-                                       size_t* offset_for_adjustment) {
+std::wstring UTF8ToWide(const base::StringPiece& utf8) {
   std::wstring ret;
-  UTF8ToWideAndAdjustOffset(utf8.data(), utf8.length(), &ret,
-                            offset_for_adjustment);
+  UTF8ToWide(utf8.data(), utf8.length(), &ret);
   return ret;
 }
 
@@ -265,20 +83,12 @@ string16 WideToUTF16(const std::wstring& wide) {
   return wide;
 }
 
-bool UTF16ToWideAndAdjustOffset(const char16* src,
-                                size_t src_len,
-                                std::wstring* output,
-                                size_t* offset_for_adjustment) {
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
   output->assign(src, src_len);
-  if (offset_for_adjustment && (*offset_for_adjustment >= src_len))
-    *offset_for_adjustment = std::wstring::npos;
   return true;
 }
 
-std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
-                                        size_t* offset_for_adjustment) {
-  if (offset_for_adjustment && (*offset_for_adjustment >= utf16.length()))
-    *offset_for_adjustment = std::wstring::npos;
+std::wstring UTF16ToWide(const string16& utf16) {
   return utf16;
 }
 
@@ -289,7 +99,7 @@ bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output) {
   // Assume that normally we won't have any non-BMP characters so the counts
   // will be the same.
   output->reserve(src_len);
-  return ConvertUnicode<wchar_t, string16>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 string16 WideToUTF16(const std::wstring& wide) {
@@ -298,23 +108,17 @@ string16 WideToUTF16(const std::wstring& wide) {
   return ret;
 }
 
-bool UTF16ToWideAndAdjustOffset(const char16* src,
-                                size_t src_len,
-                                std::wstring* output,
-                                size_t* offset_for_adjustment) {
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output) {
   output->clear();
   // Assume that normally we won't have any non-BMP characters so the counts
   // will be the same.
   output->reserve(src_len);
-  return ConvertUnicode<char16, std::wstring>(src, src_len, output,
-                                              offset_for_adjustment);
+  return ConvertUnicode(src, src_len, output);
 }
 
-std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
-                                        size_t* offset_for_adjustment) {
+std::wstring UTF16ToWide(const string16& utf16) {
   std::wstring ret;
-  UTF16ToWideAndAdjustOffset(utf16.data(), utf16.length(), &ret,
-                             offset_for_adjustment);
+  UTF16ToWide(utf16.data(), utf16.length(), &ret);
   return ret;
 }
 
@@ -326,7 +130,7 @@ std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
 
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output) {
   PrepareForUTF16Or32Output(src, src_len, output);
-  return ConvertUnicode<char, string16>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 string16 UTF8ToUTF16(const std::string& utf8) {
@@ -339,7 +143,7 @@ string16 UTF8ToUTF16(const std::string& utf8) {
 
 bool UTF16ToUTF8(const char16* src, size_t src_len, std::string* output) {
   PrepareForUTF8Output(src, src_len, output);
-  return ConvertUnicode<char16, std::string>(src, src_len, output, NULL);
+  return ConvertUnicode(src, src_len, output);
 }
 
 std::string UTF16ToUTF8(const string16& utf16) {
diff --git a/base/utf_string_conversions.h b/base/utf_string_conversions.h
index 7069f83..71e2cb2 100644
--- a/base/utf_string_conversions.h
+++ b/base/utf_string_conversions.h
@@ -8,26 +8,10 @@
 #include <string>
 
 #include "base/string16.h"
-#include "base/string_piece.h"
 
-// Like the conversions below, but also takes an offset into the source string,
-// which will be adjusted to point at the same logical place in the result
-// string.  If this isn't possible because it points past the end of the source
-// string or into the middle of a multibyte sequence, it will be set to
-// std::wstring::npos.  |offset_for_adjustment| may be NULL.
-bool UTF8ToWideAndAdjustOffset(const char* src,
-                               size_t src_len,
-                               std::wstring* output,
-                               size_t* offset_for_adjustment);
-std::wstring UTF8ToWideAndAdjustOffset(const base::StringPiece& utf8,
-                                       size_t* offset_for_adjustment);
-
-bool UTF16ToWideAndAdjustOffset(const char16* src,
-                                size_t src_len,
-                                std::wstring* output,
-                                size_t* offset_for_adjustment);
-std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
-                                        size_t* offset_for_adjustment);
+namespace base {
+class StringPiece;
+}
 
 // These convert between UTF-8, -16, and -32 strings. They are potentially slow,
 // so avoid unnecessary conversions. The low-level versions return a boolean
@@ -44,22 +28,13 @@ std::wstring UTF16ToWideAndAdjustOffset(const string16& utf16,
 // some situations.
 bool WideToUTF8(const wchar_t* src, size_t src_len, std::string* output);
 std::string WideToUTF8(const std::wstring& wide);
-inline bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output) {
-  return UTF8ToWideAndAdjustOffset(src, src_len, output, NULL);
-}
-inline std::wstring UTF8ToWide(const base::StringPiece& utf8) {
-  return UTF8ToWideAndAdjustOffset(utf8, NULL);
-}
+bool UTF8ToWide(const char* src, size_t src_len, std::wstring* output);
+std::wstring UTF8ToWide(const base::StringPiece& utf8);
 
 bool WideToUTF16(const wchar_t* src, size_t src_len, string16* output);
 string16 WideToUTF16(const std::wstring& wide);
-inline bool UTF16ToWide(const char16* src, size_t src_len,
-                        std::wstring* output) {
-  return UTF16ToWideAndAdjustOffset(src, src_len, output, NULL);
-}
-inline std::wstring UTF16ToWide(const string16& utf16) {
-  return UTF16ToWideAndAdjustOffset(utf16, NULL);
-}
+bool UTF16ToWide(const char16* src, size_t src_len, std::wstring* output);
+std::wstring UTF16ToWide(const string16& utf16);
 
 bool UTF8ToUTF16(const char* src, size_t src_len, string16* output);
 string16 UTF8ToUTF16(const std::string& utf8);
diff --git a/base/utf_string_conversions_unittest.cc b/base/utf_string_conversions_unittest.cc
index ca79ec5..19189971 100644
--- a/base/utf_string_conversions_unittest.cc
+++ b/base/utf_string_conversions_unittest.cc
@@ -226,47 +226,4 @@ TEST(UTFStringConversionsTest, ConvertMultiString) {
   EXPECT_EQ(expected, converted);
 }
 
-TEST(UTFStringConversionsTest, AdjustOffset) {
-  struct UTF8ToWideCase {
-    const char* utf8;
-    size_t input_offset;
-    size_t output_offset;
-  } utf8_to_wide_cases[] = {
-    {"", 0, std::wstring::npos},
-    {"\xe4\xbd\xa0\xe5\xa5\xbd", 1, std::wstring::npos},
-    {"\xe4\xbd\xa0\xe5\xa5\xbd", 3, 1},
-    {"\xed\xb0\x80z", 3, 0},
-    {"A\xF0\x90\x8C\x80z", 1, 1},
-    {"A\xF0\x90\x8C\x80z", 2, std::wstring::npos},
-#if defined(WCHAR_T_IS_UTF16)
-    {"A\xF0\x90\x8C\x80z", 5, 3},
-#elif defined(WCHAR_T_IS_UTF32)
-    {"A\xF0\x90\x8C\x80z", 5, 2},
-#endif
-  };
-  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf8_to_wide_cases); ++i) {
-    size_t offset = utf8_to_wide_cases[i].input_offset;
-    UTF8ToWideAndAdjustOffset(utf8_to_wide_cases[i].utf8, &offset);
-    EXPECT_EQ(utf8_to_wide_cases[i].output_offset, offset);
-  }
-
-#if defined(WCHAR_T_IS_UTF32)
-  struct UTF16ToWideCase {
-    const wchar_t* wide;
-    size_t input_offset;
-    size_t output_offset;
-  } utf16_to_wide_cases[] = {
-    {L"\xD840\xDC00\x4E00", 0, 0},
-    {L"\xD840\xDC00\x4E00", 1, std::wstring::npos},
-    {L"\xD840\xDC00\x4E00", 2, 1},
-  };
-  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(utf16_to_wide_cases); ++i) {
-    size_t offset = utf16_to_wide_cases[i].input_offset;
-    UTF16ToWideAndAdjustOffset(BuildString16(utf16_to_wide_cases[i].wide),
-                               &offset);
-    EXPECT_EQ(utf16_to_wide_cases[i].output_offset, offset);
-  }
-#endif
-}
-
 }  // namaspace base