gdata: Fix "save as pdf" to work on Google Drive.

chrome/browser/chromeos/gdata/gdata_file_write_helper.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/chromeos/gdata/gdata_file_write_helper.h"
+
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/public/browser/browser_thread.h"
+
+using content::BrowserThread;
+
+namespace gdata {
+
+GDataFileWriteHelper::GDataFileWriteHelper(
+    GDataFileSystemInterface* file_system)
+    : file_system_(file_system),
+      weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
+  // Must be created in GDataSystemService.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+}
+
+GDataFileWriteHelper::~GDataFileWriteHelper() {
+  // Must be destroyed in GDataSystemService.
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+}
+
+void GDataFileWriteHelper::PrepareWritableFileAndRun(
+    const FilePath& file_path,
+    const OpenFileCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI) ||
+         BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // TODO(kinaba): factor out RunTaskOnThread family from gdata_file_system.cc
+  // and use it.
+  if (BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+    PrepareWritableFileAndRunOnUIThread(file_path, callback);
+  } else {
+    BrowserThread::GetMessageLoopProxyForThread(BrowserThread::UI)->PostTask(
+        FROM_HERE,
+        base::Bind(&GDataFileWriteHelper::PrepareWritableFileAndRunOnUIThread,
+                   weak_ptr_factory_.GetWeakPtr(),

[satorux1, 2012/08/02 06:56:53]

ah, I was wrong. If you are to post a task to UI thread, you shouldn't use
GetWeakPtr(). Please create ui_weak_ptr in the constructor...

[satorux1, 2012/08/02 06:59:16]

Another option. As of of now, there is only one caller of this function. If the
caller is on UI thread, we should get rid of the redirection logic. We can add
it back when it's needed. YAGNI.

[kinaba, 2012/08/02 07:22:39]

Took the latter option.
I'll soon add another client (crbug.com/138593) but it also lives in the UI
thread.

+                   file_path,
+                   callback));
+  }
+}
+
+void GDataFileWriteHelper::PrepareWritableFileAndRunOnUIThread(
+    const FilePath& file_path,
+    const OpenFileCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  file_system_->CreateFile(
+      file_path,
+      false, // it is not an error, even if the path already exists.
+      base::Bind(
+          &GDataFileWriteHelper::PrepareWritableFileAndRunAfterCreateFile,
+          weak_ptr_factory_.GetWeakPtr(),
+          file_path,
+          callback));
+}
+
+void GDataFileWriteHelper::PrepareWritableFileAndRunAfterCreateFile(
+    const FilePath& file_path,
+    const OpenFileCallback& callback,
+    GDataFileError error) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (error != gdata::GDATA_FILE_OK) {
+    if (!callback.is_null()) {
+      content::BrowserThread::GetBlockingPool()->PostTask(
+          FROM_HERE,
+          base::Bind(callback, error, FilePath()));
+    }
+    return;
+  }
+  file_system_->OpenFile(
+      file_path,
+      base::Bind(&GDataFileWriteHelper::PrepareWritableFileAndRunAfterOpenFile,
+                 weak_ptr_factory_.GetWeakPtr(),
+                 file_path,
+                 callback));
+}
+
+void GDataFileWriteHelper::PrepareWritableFileAndRunAfterOpenFile(
+    const FilePath& file_path,
+    const OpenFileCallback& callback,
+    GDataFileError error,
+    const FilePath& local_cache_path) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (error != gdata::GDATA_FILE_OK) {
+    if (!callback.is_null()) {
+      content::BrowserThread::GetBlockingPool()->PostTask(
+          FROM_HERE,
+          base::Bind(callback, error, FilePath()));
+    }
+    return;
+  }
+
+  if (!callback.is_null()) {
+    content::BrowserThread::GetBlockingPool()->PostTaskAndReply(
+        FROM_HERE,
+        base::Bind(callback, GDATA_FILE_OK, local_cache_path),
+        base::Bind(
+            &GDataFileWriteHelper::PrepareWritableFileAndRunAfterCallback,
+            weak_ptr_factory_.GetWeakPtr(),
+            file_path));
+  } else {
+    PrepareWritableFileAndRunAfterCallback(file_path);
+  }
+}
+
+void GDataFileWriteHelper::PrepareWritableFileAndRunAfterCallback(
+    const FilePath& file_path) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  file_system_->CloseFile(file_path, FileOperationCallback());
+}
+
+}  // namespace gdata