Check crostini deleted paths on threadpool, not IO thread

I erroneously used the IO thread for checking if paths exist
when first creating this code.

Change-Id: I2f0180be7e4ad7caec4d11a28bf3e434533a6e94
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1619444
Auto-Submit: Joel Hockey <joelhockey@chromium.org>
Commit-Queue: Nicholas Verne <nverne@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661274}

chrome/browser/chromeos/crostini/crostini_share_path.cc

@@ -602,14 +602,12 @@ void CrostiniSharePath::OnFileChanged(const base::FilePath& path, bool error) {
     return;
   }
   base::PostTaskWithTraits(
-      FROM_HERE, {content::BrowserThread::IO},
-      base::BindOnce(&CrostiniSharePath::CheckIfPathDeletedOnIOThread,
+      FROM_HERE, {base::MayBlock()},
+      base::BindOnce(&CrostiniSharePath::CheckIfPathDeleted,
                      base::Unretained(this), path));
 }
 
-void CrostiniSharePath::CheckIfPathDeletedOnIOThread(
-    const base::FilePath& path) {
-  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+void CrostiniSharePath::CheckIfPathDeleted(const base::FilePath& path) {
   if (base::PathExists(path)) {
     return;
   }

chrome/browser/chromeos/crostini/crostini_share_path.h

@@ -155,8 +155,8 @@ class CrostiniSharePath : public KeyedService,
   // Callback for FilePathWatcher.
   void OnFileChanged(const base::FilePath& path, bool error);
 
-  // Runs on IO Thread to check if a path is deleted.
-  void CheckIfPathDeletedOnIOThread(const base::FilePath& path);
+  // Blocking function to check if a path is deleted.
+  void CheckIfPathDeleted(const base::FilePath& path);
 
   // Returns info for specified path or nullptr if not found.
   SharedPathInfo* FindSharedPathInfo(const base::FilePath& path);