Add new SplitString backend.

base/strings/string_util.h

Index: base/strings/string_util.h
diff --git a/base/strings/string_util.h b/base/strings/string_util.h
index bea44ae8fddbaa0992d2d76b5d2719950df70e1d..42d3aa2380390fd47363f224a1e2fae52ccf0372 100644
--- a/base/strings/string_util.h
+++ b/base/strings/string_util.h
@@ -138,10 +138,12 @@ BASE_EXPORT const std::string& EmptyString();
 BASE_EXPORT const string16& EmptyString16();
 
 // Contains the set of characters representing whitespace in the corresponding
-// encoding. Null-terminated.
-BASE_EXPORT extern const wchar_t kWhitespaceWide[];
-BASE_EXPORT extern const char16 kWhitespaceUTF16[];
+// encoding. Null-terminated. The ASCII versions are the whitespaces as defined
+// by HTML5, and don't include control characters.
+BASE_EXPORT extern const wchar_t kWhitespaceWide[];  // Includes Unicode.
+BASE_EXPORT extern const char16 kWhitespaceUTF16[];  // Includes Unicode.
 BASE_EXPORT extern const char kWhitespaceASCII[];
+BASE_EXPORT extern const char16 kWhitespaceASCIIAs16[];  // No unicode.
 
 // Null-terminated string representing the UTF-8 byte order mark.
 BASE_EXPORT extern const char kUtf8ByteOrderMark[];
@@ -170,16 +172,34 @@ BASE_EXPORT bool ReplaceChars(const std::string& input,
                               const std::string& replace_with,
                               std::string* output);
 
+enum TrimPositions {
+  TRIM_NONE     = 0,
+  TRIM_LEADING  = 1 << 0,
+  TRIM_TRAILING = 1 << 1,
+  TRIM_ALL      = TRIM_LEADING | TRIM_TRAILING,
+};
+
 // Removes characters in |trim_chars| from the beginning and end of |input|.
-// |trim_chars| must be null-terminated.
-// NOTE: Safe to use the same variable for both |input| and |output|.
+// The 8-bit version only works on 8-bit characters, not UTF-8.
+//
+// It is safe to use the same variable for both |input| and |output| (this is
+// the normal usage to trim in-place).
 BASE_EXPORT bool TrimString(const string16& input,
-                            const base::StringPiece16& trim_chars,
+                            base::StringPiece16 trim_chars,
                             string16* output);
 BASE_EXPORT bool TrimString(const std::string& input,
-                            const base::StringPiece& trim_chars,
+                            base::StringPiece trim_chars,
                             std::string* output);
 
+// StringPiece versions of the above. The returned pieces refer to the original
+// buffer.
+BASE_EXPORT StringPiece16 TrimString(StringPiece16 input,
+                                     const base::StringPiece16& trim_chars,
+                                     TrimPositions positions);
+BASE_EXPORT StringPiece TrimString(StringPiece input,
+                                   const base::StringPiece& trim_chars,
+                                   TrimPositions positions);
+
 // Truncates a string to the nearest UTF-8 character that will leave
 // the string less than or equal to the specified byte size.
 BASE_EXPORT void TruncateUTF8ToByteSize(const std::string& input,
@@ -193,12 +213,6 @@ BASE_EXPORT void TruncateUTF8ToByteSize(const std::string& input,
 //   This function is for ASCII strings and only looks for ASCII whitespace;
 // Please choose the best one according to your usage.
 // NOTE: Safe to use the same variable for both input and output.
-enum TrimPositions {
-  TRIM_NONE     = 0,
-  TRIM_LEADING  = 1 << 0,
-  TRIM_TRAILING = 1 << 1,
-  TRIM_ALL      = TRIM_LEADING | TRIM_TRAILING,
-};
 BASE_EXPORT TrimPositions TrimWhitespace(const string16& input,
                                          TrimPositions positions,
                                          base::string16* output);
@@ -450,6 +464,9 @@ inline typename string_type::value_type* WriteInto(string_type* str,
 // Splits a string into its fields delimited by any of the characters in
 // |delimiters|.  Each field is added to the |tokens| vector.  Returns the
 // number of tokens found.
+//
+// DEPRECATED. Use SplitStringUsingSet for new code (these just forward).
+// TODO(brettw) convert callers and delete these forwarders.
 BASE_EXPORT size_t Tokenize(const base::string16& str,
                             const base::string16& delimiters,
                             std::vector<base::string16>* tokens);