Add utility method for WebString to base::FilePath conversion

base/files/file_path.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 "base/files/file_path.h"
 
 #include <string.h>
 #include <algorithm>
 
 #include "base/logging.h"
@@ skipping 592 matching lines @@
 
 string16 FilePath::AsUTF16Unsafe() const {
 #if defined(SYSTEM_NATIVE_UTF8)
   return UTF8ToUTF16(value());
 #else
   return WideToUTF16(SysNativeMBToWide(value()));
 #endif
 }
 
 // static
-FilePath FilePath::FromUTF8Unsafe(const std::string& utf8) {
+FilePath FilePath::FromUTF8Unsafe(StringPiece utf8) {
 #if defined(SYSTEM_NATIVE_UTF8)
   return FilePath(utf8);
 #else
   return FilePath(SysWideToNativeMB(UTF8ToWide(utf8)));
 #endif
 }
 
 // static
-FilePath FilePath::FromUTF16Unsafe(const string16& utf16) {
+FilePath FilePath::FromUTF16Unsafe(StringPiece16 utf16) {
 #if defined(SYSTEM_NATIVE_UTF8)
   return FilePath(UTF16ToUTF8(utf16));
 #else
-  return FilePath(SysWideToNativeMB(UTF16ToWide(utf16)));
+  return FilePath(SysWideToNativeMB(UTF16ToWide(utf16.as_string())));
 #endif
 }
 
 #elif defined(OS_WIN)
 string16 FilePath::LossyDisplayName() const {
   return path_;
 }
 
 std::string FilePath::MaybeAsASCII() const {
   if (base::IsStringASCII(path_))
     return UTF16ToASCII(path_);
   return std::string();
 }
 
 std::string FilePath::AsUTF8Unsafe() const {
   return WideToUTF8(value());
 }
 
 string16 FilePath::AsUTF16Unsafe() const {
   return value();
 }
 
 // static
-FilePath FilePath::FromUTF8Unsafe(const std::string& utf8) {
+FilePath FilePath::FromUTF8Unsafe(StringPiece utf8) {
   return FilePath(UTF8ToWide(utf8));
 }
 
 // static
-FilePath FilePath::FromUTF16Unsafe(const string16& utf16) {
+FilePath FilePath::FromUTF16Unsafe(StringPiece16 utf16) {
   return FilePath(utf16);
 }
 #endif
 
 void FilePath::GetSizeForPickle(PickleSizer* sizer) const {
 #if defined(OS_WIN)
   sizer->AddString16(path_);
 #else
   sizer->AddString(path_);
 #endif
@@ skipping 655 matching lines @@
 #endif
 }
 
 #if defined(OS_ANDROID)
 bool FilePath::IsContentUri() const {
   return StartsWith(path_, "content://", base::CompareCase::INSENSITIVE_ASCII);
 }
 #endif
 
 }  // namespace base