Move more uses of string16 to specify base::

ui/gfx/utf16_indexing.cc

 // Copyright (c) 2012 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 "ui/gfx/utf16_indexing.h"
 
 #include "base/logging.h"
 #include "base/third_party/icu/icu_utf.h"
 
 namespace gfx {
 
-bool IsValidCodePointIndex(const string16& s, size_t index) {
+bool IsValidCodePointIndex(const base::string16& s, size_t index) {
   return index == 0 || index == s.length() ||
     !(CBU16_IS_TRAIL(s[index]) && CBU16_IS_LEAD(s[index - 1]));
 }
 
-ptrdiff_t UTF16IndexToOffset(const string16& s, size_t base, size_t pos) {
+ptrdiff_t UTF16IndexToOffset(const base::string16& s, size_t base, size_t pos) {
   // The indices point between UTF-16 words (range 0 to s.length() inclusive).
   // In order to consistently handle indices that point to the middle of a
   // surrogate pair, we count the first word in that surrogate pair and not
   // the second. The test "s[i] is not the second half of a surrogate pair" is
   // "IsValidCodePointIndex(s, i)".
   DCHECK_LE(base, s.length());
   DCHECK_LE(pos, s.length());
   ptrdiff_t delta = 0;
   while (base < pos)
     delta += IsValidCodePointIndex(s, base++) ? 1 : 0;
   while (pos < base)
     delta -= IsValidCodePointIndex(s, pos++) ? 1 : 0;
   return delta;
 }
 
-size_t UTF16OffsetToIndex(const string16& s, size_t base, ptrdiff_t offset) {
+size_t UTF16OffsetToIndex(const base::string16& s,
+                          size_t base,
+                          ptrdiff_t offset) {
   DCHECK_LE(base, s.length());
   // As in UTF16IndexToOffset, we count the first half of a surrogate pair, not
   // the second. When stepping from pos to pos+1 we check s[pos:pos+1] == s[pos]
   // (Python syntax), hence pos++. When stepping from pos to pos-1 we check
   // s[pos-1], hence --pos.
   size_t pos = base;
   while (offset > 0 && pos < s.length())
     offset -= IsValidCodePointIndex(s, pos++) ? 1 : 0;
   while (offset < 0 && pos > 0)
     offset += IsValidCodePointIndex(s, --pos) ? 1 : 0;
   // If offset != 0 then we ran off the edge of the string, which is a contract
   // violation but is handled anyway (by clamping) in release for safety.
   DCHECK_EQ(offset, 0);
   // Since the second half of a surrogate pair has "length" zero, there is an
   // ambiguity in the returned position. Resolve it by always returning a valid
   // index.
   if (!IsValidCodePointIndex(s, pos))
     ++pos;
   return pos;
 }
 
 }  // namespace gfx