Handle errors properly in FileUtilProxy::CreateTemporary.

If creating the temporary file failed, don't try to open it. If we can't open
it for some reason, delete the temporary so the caller can assume strong
exception safety and not have to delete the file on error.

BUG=none

Review URL: https://codereview.chromium.org/183003009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255767 0039d316-1c4b-4281-b951-d872f2087c98

base/files/file_util_proxy.cc

@@ -77,7 +77,12 @@ class CreateTemporaryHelper {
   void RunWork(int additional_file_flags) {
     // TODO(darin): file_util should have a variant of CreateTemporaryFile
     // that returns a FilePath and a PlatformFile.
-    base::CreateTemporaryFile(&file_path_);
+    if (!base::CreateTemporaryFile(&file_path_)) {
+      // TODO(davidben): base::CreateTemporaryFile should preserve the error
+      // code.
+      error_ = File::FILE_ERROR_FAILED;
+      return;
+    }
 
     int file_flags =
         PLATFORM_FILE_WRITE |
@@ -90,6 +95,10 @@ class CreateTemporaryHelper {
     file_handle_ =
         CreatePlatformFile(file_path_, file_flags, NULL,
                            reinterpret_cast<PlatformFileError*>(&error_));
+    if (error_ != File::FILE_OK) {
+      base::DeleteFile(file_path_, false);
+      file_path_.clear();
+    }
   }
 
   void Reply(const FileUtilProxy::CreateTemporaryCallback& callback) {