FilePath: Remove much of ToWStringHack, adding a LossyDisplayName()

The reason we don't want a free conversion between FilePaths and Unicode
is that it can be lossy.  But when displaying a string to the user,
we're ok if it's lossy when we have no other option.

This change introduces a LossyDisplayName() method that returns a
string16, and converts many of the users of ToWStringHack to use it.

BUG=69467

Review URL: http://codereview.chromium.org/6246036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@73840 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 22 insertions, 5 deletions

diff --git a/base/file_path.cc b/base/file_path.cc
index 9bc46f0..5f1375a 100644
--- a/base/file_path.cc
+++ b/base/file_path.cc
@@ -513,10 +513,14 @@ bool FilePath::ReferencesParent() const {
 }
 
 #if defined(OS_POSIX)
-
 // See file_path.h for a discussion of the encoding of paths on POSIX
-// platforms.  These *Hack() functions are not quite correct, but they're
-// only temporary while we fix the remainder of the code.
+// platforms.  These encoding conversion functions are not quite correct.
+
+string16 FilePath::LossyDisplayName() const {
+  return WideToUTF16(base::SysNativeMBToWide(path_));
+}
+
+// The *Hack functions are temporary while we fix the remainder of the code.
 // Remember to remove the #includes at the top when you remove these.
 
 // static
@@ -527,6 +531,10 @@ std::wstring FilePath::ToWStringHack() const {
   return base::SysNativeMBToWide(path_);
 }
 #elif defined(OS_WIN)
+string16 FilePath::LossyDisplayName() const {
+  return path_;
+}
+
 // static
 FilePath FilePath::FromWStringHack(const std::wstring& wstring) {
   return FilePath(wstring);
diff --git a/base/file_path.h b/base/file_path.h
index 01cd4a5..84bb350 100644
--- a/base/file_path.h
+++ b/base/file_path.h
@@ -277,6 +277,12 @@ class FilePath {
   // directory (i.e. has a path component that is ".."
   bool ReferencesParent() const;
 
+  // Return a Unicode human-readable version of this path.
+  // Warning: you can *not*, in general, go from a display name back to a real
+  // path.  Only use this when displaying paths to users, not just when you
+  // want to stuff a string16 into some other API.
+  string16 LossyDisplayName() const;
+
   // Older Chromium code assumes that paths are always wstrings.
   // These functions convert wstrings to/from FilePaths, and are
   // useful to smooth porting that old code to the FilePath API.
@@ -290,6 +296,9 @@ class FilePath {
   //   OS-native string format.
   // - Am I using well-known file names, like "config.ini"?  Then use the
   //   ASCII functions (we require paths to always be supersets of ASCII).
+  // - Am I displaying a string to the user in some UI?  Then use the
+  //   LossyDisplayName() function, but keep in mind that you can't
+  //   ever use the result of that again as a path.
   static FilePath FromWStringHack(const std::wstring& wstring);
   std::wstring ToWStringHack() const;
 
diff --git a/base/file_util_unittest.cc b/base/file_util_unittest.cc
index 6ea94e4..ea29df5 100644
--- a/base/file_util_unittest.cc
+++ b/base/file_util_unittest.cc
@@ -163,7 +163,7 @@ class FindResultCollector {
 void CreateTextFile(const FilePath& filename,
                     const std::wstring& contents) {
   std::ofstream file;
-  file.open(WideToUTF8(filename.ToWStringHack()).c_str());
+  file.open(filename.value().c_str());
   ASSERT_TRUE(file.is_open());
   file << contents;
   file.close();
@@ -173,7 +173,7 @@ void CreateTextFile(const FilePath& filename,
 std::wstring ReadTextFile(const FilePath& filename) {
   wchar_t contents[64];
   std::wifstream file;
-  file.open(WideToUTF8(filename.ToWStringHack()).c_str());
+  file.open(filename.value().c_str());
   EXPECT_TRUE(file.is_open());
   file.getline(contents, 64);
   file.close();