Use TaskScheduler instead of blocking pool in content_hash_fetcher.cc.

extensions/browser/content_hash_fetcher.cc

Index: extensions/browser/content_hash_fetcher.cc
diff --git a/extensions/browser/content_hash_fetcher.cc b/extensions/browser/content_hash_fetcher.cc
index 7962630b26352f41dc0df07a19e442ea68a71d58..d179d997e9a1afb83d43c61f4d3797f33df57423 100644
--- a/extensions/browser/content_hash_fetcher.cc
+++ b/extensions/browser/content_hash_fetcher.cc
@@ -18,8 +18,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/synchronization/lock.h"
-#include "base/task_runner_util.h"
-#include "base/threading/sequenced_worker_pool.h"
+#include "base/task_scheduler/post_task.h"
 #include "base/timer/elapsed_timer.h"
 #include "base/version.h"
 #include "content/public/browser/browser_thread.h"
@@ -196,11 +195,10 @@ ContentHashFetcherJob::ContentHashFetcherJob(
 void ContentHashFetcherJob::Start() {
   base::FilePath verified_contents_path =
       file_util::GetVerifiedContentsPath(extension_path_);
-  base::PostTaskAndReplyWithResult(
-      content::BrowserThread::GetBlockingPool(),
-      FROM_HERE,
-      base::Bind(&ContentHashFetcherJob::LoadVerifiedContents,
-                 this,
+  base::PostTaskWithTraitsAndReplyWithResult(
+      FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
+                     base::TaskPriority::USER_VISIBLE),
+      base::Bind(&ContentHashFetcherJob::LoadVerifiedContents, this,
                  verified_contents_path),
       base::Bind(&ContentHashFetcherJob::DoneCheckingForVerifiedContents,
                  this));
@@ -289,12 +287,12 @@ void ContentHashFetcherJob::OnURLFetchComplete(const net::URLFetcher* source) {
     base::FilePath destination =
         file_util::GetVerifiedContentsPath(extension_path_);
     size_t size = response->size();
-    base::PostTaskAndReplyWithResult(
-        content::BrowserThread::GetBlockingPool(),
-        FROM_HERE,
+    base::PostTaskWithTraitsAndReplyWithResult(
+        FROM_HERE, base::TaskTraits().MayBlock().WithPriority(
+                       base::TaskPriority::BACKGROUND),

[Devlin, 2017/02/16 16:59:42]

ditto:
USER_VISIBLE

This is in response to loading an extension, and may result in the extension
becoming disabled or notifying the user of corruption.

(Would have mentioned this in the previous patch set, but this wasn't changed in
PS2)

         base::Bind(&WriteFileHelper, destination, base::Passed(&response)),
-        base::Bind(
-            &ContentHashFetcherJob::OnVerifiedContentsWritten, this, size));
+        base::Bind(&ContentHashFetcherJob::OnVerifiedContentsWritten, this,
+                   size));
   } else {
     DoneFetchingVerifiedContents(false);
   }