Manage fan-in for writable file entry checking on the UI thread.

chrome/browser/extensions/api/file_system/file_system_api.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 "chrome/browser/extensions/api/file_system/file_system_api.h"
 
 #include "apps/saved_files_service.h"
 #include "apps/shell_window.h"
 #include "base/bind.h"
 #include "base/file_util.h"
@@ skipping 297 matching lines @@
         content::BrowserThread::FILE,
         FROM_HERE,
         base::Bind(&WritableFileChecker::CheckLocalWritableFiles, this, paths));
   }
 
  private:
   friend class base::RefCountedThreadSafe<WritableFileChecker>;
   virtual ~WritableFileChecker() {}
 
   // Called when a work item is completed. If all work items are done, this
-  // posts a task to run AllTasksDone on the UI thread.
+  // calls the success or failure callback.
   void TaskDone() {
-    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
+    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
     if (--outstanding_tasks_ == 0) {
-      content::BrowserThread::PostTask(
-          content::BrowserThread::UI,
-          FROM_HERE,
-          base::Bind(&WritableFileChecker::AllTasksDone, this));
+      if (error_.empty())
+        on_success_.Run();
+      else
+        on_failure_.Run(error_);
     }
   }
 
-  // Called on the UI thread when all tasks are done.
-  void AllTasksDone() {
-    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
-    if (error_.empty())
-      on_success_.Run();
-    else
-      on_failure_.Run(error_);
-  }
-
   // Reports an error in completing a work item. This may be called more than
   // once, but only the last message will be retained.
   void Error(const std::string& message) {
-    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
     DCHECK(!message.empty());
     error_ = message;
     TaskDone();
   }
 
   void CheckLocalWritableFiles(const std::vector<base::FilePath>& paths) {
     DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
     std::string error;
     for (std::vector<base::FilePath>::const_iterator it = paths.begin();
          it != paths.end(); ++it) {
       if (!DoCheckWritableFile(*it, extension_path_, &error)) {
-        Error(error);
+        content::BrowserThread::PostTask(
+            content::BrowserThread::UI,
+            FROM_HERE,
+            base::Bind(&WritableFileChecker::Error, this, error));
         return;
       }
     }
-    TaskDone();
+    content::BrowserThread::PostTask(
+        content::BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(&WritableFileChecker::TaskDone, this));
   }
 
 #if defined(OS_CHROMEOS)
   void CheckRemoteWritableFile(drive::FileError error,
                                const base::FilePath& path) {
-    DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::FILE));
     if (error == drive::FILE_ERROR_OK) {
-      TaskDone();
+      content::BrowserThread::PostTask(
+          content::BrowserThread::UI,
+          FROM_HERE,
+          base::Bind(&WritableFileChecker::TaskDone, this));
     } else {
-      Error(base::StringPrintf(kWritableFileErrorFormat,
-                               path.BaseName().AsUTF8Unsafe().c_str()));
+      content::BrowserThread::PostTask(
+          content::BrowserThread::UI,
+          FROM_HERE,
+          base::Bind(
+              &WritableFileChecker::Error,
+              this,
+              base::StringPrintf(kWritableFileErrorFormat,
+                                 path.BaseName().AsUTF8Unsafe().c_str())));
     }
   }
 #endif
 
   int outstanding_tasks_;
   const base::FilePath extension_path_;
   std::string error_;
   base::Closure on_success_;
   base::Callback<void(const std::string&)> on_failure_;
 };
@@ skipping 647 matching lines @@
   if (needs_new_entry) {
     entry_type_ = file_entry->writable ? WRITABLE : READ_ONLY;
     CreateResponse();
     AddEntryToResponse(file_entry->path, file_entry->id);
   }
   SendResponse(true);
   return true;
 }
 
 }  // namespace extensions