Convert PpdCache and PpdProvider to TaskScheduler.

chromeos/printing/ppd_provider.cc

Index: chromeos/printing/ppd_provider.cc
diff --git a/chromeos/printing/ppd_provider.cc b/chromeos/printing/ppd_provider.cc
index aa62d8b35c737ca08ee08911e5d6f78b4f9c4d6c..bb6ea89b0396edb4ae70b3968e43a3b6b43f5c46 100644
--- a/chromeos/printing/ppd_provider.cc
+++ b/chromeos/printing/ppd_provider.cc
@@ -17,6 +17,7 @@
 #include "base/files/file_util.h"
 #include "base/json/json_parser.h"
 #include "base/memory/ptr_util.h"
+#include "base/sequenced_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_tokenizer.h"
@@ -24,6 +25,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/synchronization/lock.h"
 #include "base/task_runner_util.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time/time.h"
@@ -201,12 +203,13 @@ class PpdProviderImpl : public PpdProvider, public net::URLFetcherDelegate {
       const std::string& browser_locale,
       scoped_refptr<net::URLRequestContextGetter> url_context_getter,
       scoped_refptr<PpdCache> ppd_cache,
-      scoped_refptr<base::SequencedTaskRunner> disk_task_runner,
       const PpdProvider::Options& options)
       : browser_locale_(browser_locale),
         url_context_getter_(url_context_getter),
         ppd_cache_(ppd_cache),
-        disk_task_runner_(disk_task_runner),
+        disk_task_runner_(base::CreateSequencedTaskRunnerWithTraits(
+            {base::TaskPriority::USER_BLOCKING,

[gab, 2017/06/19 15:13:22]

Are you sure this is USER_BLOCKING? It was previously using the FILE thread
which wasn't appropriate for user blocking work (was that a bug?)

[skau, 2017/06/19 23:31:08]

No.  This should have been USER_VISIBLE.  It is now fixed.

+             base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN})),
         options_(options),
         weak_factory_(this) {}
 
@@ -1001,11 +1004,9 @@ scoped_refptr<PpdProvider> PpdProvider::Create(
     const std::string& browser_locale,
     scoped_refptr<net::URLRequestContextGetter> url_context_getter,
     scoped_refptr<PpdCache> ppd_cache,
-    scoped_refptr<base::SequencedTaskRunner> disk_task_runner,
     const PpdProvider::Options& options) {
-  return scoped_refptr<PpdProvider>(
-      new PpdProviderImpl(browser_locale, url_context_getter, ppd_cache,
-                          disk_task_runner, options));
+  return scoped_refptr<PpdProvider>(new PpdProviderImpl(
+      browser_locale, url_context_getter, ppd_cache, options));
 }
 }  // namespace printing
 }  // namespace chromeos