[fsp] Convert base::File::Error to string.

This patch adds a utility function which converts a base::File::Error code
to a human readable form. It will be used for logging request errors in the
File System Provider API.

TEST=Not used yet.
BUG=376095

Review URL: https://codereview.chromium.org/308613002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@273779 0039d316-1c4b-4281-b951-d872f2087c98

base/files/file.cc

@@ -85,4 +85,48 @@ void File::Initialize(const FilePath& name, uint32 flags) {
 }
 #endif
 
+std::string File::ErrorToString(Error error) {
+  switch (error) {
+    case FILE_OK:
+      return "FILE_OK";
+    case FILE_ERROR_FAILED:
+      return "FILE_ERROR_FAILED";
+    case FILE_ERROR_IN_USE:
+      return "FILE_ERROR_IN_USE";
+    case FILE_ERROR_EXISTS:
+      return "FILE_ERROR_EXISTS";
+    case FILE_ERROR_NOT_FOUND:
+      return "FILE_ERROR_NOT_FOUND";
+    case FILE_ERROR_ACCESS_DENIED:
+      return "FILE_ERROR_ACCESS_DENIED";
+    case FILE_ERROR_TOO_MANY_OPENED:
+      return "FILE_ERROR_TOO_MANY_OPENED";
+    case FILE_ERROR_NO_MEMORY:
+      return "FILE_ERROR_NO_MEMORY";
+    case FILE_ERROR_NO_SPACE:
+      return "FILE_ERROR_NO_SPACE";
+    case FILE_ERROR_NOT_A_DIRECTORY:
+      return "FILE_ERROR_NOT_A_DIRECTORY";
+    case FILE_ERROR_INVALID_OPERATION:
+      return "FILE_ERROR_INVALID_OPERATION";
+    case FILE_ERROR_SECURITY:
+      return "FILE_ERROR_SECURITY";
+    case FILE_ERROR_ABORT:
+      return "FILE_ERROR_ABORT";
+    case FILE_ERROR_NOT_A_FILE:
+      return "FILE_ERROR_NOT_A_FILE";
+    case FILE_ERROR_NOT_EMPTY:
+      return "FILE_ERROR_NOT_EMPTY";
+    case FILE_ERROR_INVALID_URL:
+      return "FILE_ERROR_INVALID_URL";
+    case FILE_ERROR_IO:
+      return "FILE_ERROR_IO";
+    case FILE_ERROR_MAX:
+      break;
+  }
+
+  NOTREACHED();
+  return "";
+}
+
 }  // namespace base

base/files/file.h

@@ -14,6 +14,8 @@
 #include <sys/stat.h>
 #endif
 
+#include <string>
+
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/files/scoped_file.h"
@@ -289,6 +291,9 @@ class BASE_EXPORT File {
   static Error OSErrorToFileError(int saved_errno);
 #endif
 
+  // Converts an error value to a human-readable form. Used for logging.
+  static std::string ErrorToString(Error error);
+
  private:
   void SetPlatformFile(PlatformFile file);