Downloads: replace BrowserThread::FILE with task scheduler.

content/browser/download/save_package.cc

Index: content/browser/download/save_package.cc
diff --git a/content/browser/download/save_package.cc b/content/browser/download/save_package.cc
index b6b6bd454ff1ab1cffd36f55fa8f70cc32dbe66c..cd6f1a079f0bff256aadaa1e2dc6ff0175ddc8ab 100644
--- a/content/browser/download/save_package.cc
+++ b/content/browser/download/save_package.cc
@@ -20,13 +20,16 @@
 #include "base/strings/string_split.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_runner_util.h"
 #include "base/threading/thread.h"
+#include "base/threading/thread_restrictions.h"
 #include "build/build_config.h"
 #include "components/url_formatter/url_formatter.h"
 #include "content/browser/bad_message.h"
 #include "content/browser/download/download_item_impl.h"
 #include "content/browser/download/download_manager_impl.h"
 #include "content/browser/download/download_stats.h"
+#include "content/browser/download/download_task_runner.h"
 #include "content/browser/download/save_file.h"
 #include "content/browser/download/save_file_manager.h"
 #include "content/browser/download/save_item.h"
@@ -632,10 +635,9 @@ void SavePackage::Stop(bool cancel_download_item) {
   for (const auto& it : saved_failed_items_)
     save_item_ids.push_back(it.first);
 
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&SaveFileManager::RemoveSavedFileFromFileMap, file_manager_,
-                 save_item_ids));
+  GetDownloadTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&SaveFileManager::RemoveSavedFileFromFileMap,
+                            file_manager_, save_item_ids));
 
   finished_ = true;
   wait_state_ = FAILED;
@@ -661,15 +663,11 @@ void SavePackage::CheckFinish() {
   for (const auto& it : saved_success_items_)
     final_names.insert(std::make_pair(it.first, it.second->full_path()));
 
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&SaveFileManager::RenameAllFiles,
-                 file_manager_,
-                 final_names,
-                 dir,
-                 web_contents()->GetRenderProcessHost()->GetID(),
-                 web_contents()->GetMainFrame()->GetRoutingID(),
-                 id()));
+  GetDownloadTaskRunner()->PostTask(
+      FROM_HERE,
+      base::Bind(&SaveFileManager::RenameAllFiles, file_manager_, final_names,
+                 dir, web_contents()->GetRenderProcessHost()->GetID(),
+                 web_contents()->GetMainFrame()->GetRoutingID(), id()));
 }
 
 // Successfully finished all items of this SavePackage.
@@ -701,10 +699,9 @@ void SavePackage::Finish() {
     list_of_failed_save_item_ids.push_back(save_item->id());
   }
 
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
-      base::Bind(&SaveFileManager::RemoveSavedFileFromFileMap, file_manager_,
-                 list_of_failed_save_item_ids));
+  GetDownloadTaskRunner()->PostTask(
+      FROM_HERE, base::Bind(&SaveFileManager::RemoveSavedFileFromFileMap,
+                            file_manager_, list_of_failed_save_item_ids));
 
   if (download_) {
     if (save_type_ != SAVE_PAGE_TYPE_AS_MHTML) {
@@ -768,8 +765,8 @@ void SavePackage::SaveFinished(SaveItemId save_item_id,
 void SavePackage::SaveCanceled(const SaveItem* save_item) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   file_manager_->RemoveSaveFile(save_item->id(), this);
-  BrowserThread::PostTask(
-      BrowserThread::FILE, FROM_HERE,
+  GetDownloadTaskRunner()->PostTask(
+      FROM_HERE,
       base::Bind(&SaveFileManager::CancelSave, file_manager_, save_item->id()));
 }
 
@@ -929,10 +926,9 @@ void SavePackage::GetSerializedHtmlWithLocalLinks() {
       number_of_frames_pending_response_++;
     } else {
       // Notify SaveFileManager about the failure to save this SaveItem.
-      BrowserThread::PostTask(
-          BrowserThread::FILE, FROM_HERE,
-          base::Bind(&SaveFileManager::SaveFinished, file_manager_,
-                     save_item->id(), id(), false));
+      GetDownloadTaskRunner()->PostTask(
+          FROM_HERE, base::Bind(&SaveFileManager::SaveFinished, file_manager_,
+                                save_item->id(), id(), false));
     }
   }
   if (number_of_frames_pending_response_ == 0) {
@@ -1043,8 +1039,8 @@ void SavePackage::OnSerializedHtmlWithLocalLinksResponse(
     memcpy(new_data->data(), data.data(), data.size());
 
     // Call write file functionality in FILE thread.
-    BrowserThread::PostTask(
-        BrowserThread::FILE, FROM_HERE,
+    GetDownloadTaskRunner()->PostTask(
+        FROM_HERE,
         base::Bind(&SaveFileManager::UpdateSaveProgress, file_manager_,
                    save_item->id(), base::RetainedRef(new_data),
                    static_cast<int>(data.size())));
@@ -1054,10 +1050,9 @@ void SavePackage::OnSerializedHtmlWithLocalLinksResponse(
   if (end_of_data) {
     DVLOG(20) << __func__ << "() save_item_id = " << save_item->id()
               << " url = \"" << save_item->url().spec() << "\"";
-    BrowserThread::PostTask(
-        BrowserThread::FILE, FROM_HERE,
-        base::Bind(&SaveFileManager::SaveFinished, file_manager_,
-                   save_item->id(), id(), true));
+    GetDownloadTaskRunner()->PostTask(
+        FROM_HERE, base::Bind(&SaveFileManager::SaveFinished, file_manager_,
+                              save_item->id(), id(), true));
     number_of_frames_pending_response_--;
     DCHECK_LE(0, number_of_frames_pending_response_);
   }
@@ -1289,7 +1284,7 @@ base::FilePath SavePackage::GetSuggestedNameForSaveAs(
 
 // static
 base::FilePath SavePackage::EnsureHtmlExtension(const base::FilePath& name) {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  base::ThreadRestrictions::AssertIOAllowed();

[boliu, 2017/07/20 18:47:35]

I suppose should replace these with both this and
DCHECK(DownloadRunner()->RunsInCurrentSequence())?

[gab, 2017/07/20 19:07:47]

I recommended going this way because 

1) They have no sequencing requirements per being static.

2) these are unit tested directly and having them
DCHECK(DownloadRunner()->RunsInCurrentSequence()) requires that the unit test
hops to test its code which is unfortunate when there isn't a real sequencing
requirement.

 
   base::FilePath::StringType ext = name.Extension();
   if (!ext.empty())
@@ -1306,7 +1301,7 @@ base::FilePath SavePackage::EnsureHtmlExtension(const base::FilePath& name) {
 // static
 base::FilePath SavePackage::EnsureMimeExtension(const base::FilePath& name,
     const std::string& contents_mime_type) {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  base::ThreadRestrictions::AssertIOAllowed();
 
   // Start extension at 1 to skip over period if non-empty.
   base::FilePath::StringType ext = name.Extension();
@@ -1359,8 +1354,8 @@ void SavePackage::GetSaveInfo() {
   }
   std::string mime_type = web_contents()->GetContentsMimeType();
   bool can_save_as_complete = CanSaveAsComplete(mime_type);
-  BrowserThread::PostTaskAndReplyWithResult(
-      BrowserThread::FILE, FROM_HERE,
+  PostTaskAndReplyWithResult(
+      GetDownloadTaskRunner().get(), FROM_HERE,
       base::Bind(&SavePackage::CreateDirectoryOnFileThread, title_, page_url_,
                  can_save_as_complete, mime_type, website_save_dir,
                  download_save_dir, skip_dir_check),
@@ -1377,7 +1372,7 @@ base::FilePath SavePackage::CreateDirectoryOnFileThread(
     const base::FilePath& website_save_dir,
     const base::FilePath& download_save_dir,
     bool skip_dir_check) {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
+  DCHECK(GetDownloadTaskRunner()->RunsTasksInCurrentSequence());
 
   base::FilePath suggested_filename = GetSuggestedNameForSaveAs(
       title, page_url, can_save_as_complete, mime_type);