[TaskScheduler]: Migrate off of AssertBlockingAllowedDeprecated in /chrome/browser/ui/app_list

base::AssertBlockingAllowedDeprecated is deprecated in favor of
ScopedBlockingCall, which serves as a precise annotation of
the scope that may/will block.

Please make sure of the following:
  - ScopedBlockingCall is instantiated in a scope with minimal CPU usage.
    If this is not the case, ScopedBlockingCall should be instantiated
    closer to the blocking call. See scoped_blocking_call.h for more
    info. Please let me know when/where the blocking call happens if this needs
    to be changed.
  - Parameter |blocking_type| matches expectation:
      MAY_BLOCK: The call might block (e.g. file I/O that might hit in memory cache).
      WILL_BLOCK: The call will definitely block (e.g. cache already checked and now pinging
        server synchronously).
    See BlockingType for more info. While I assumed MAY_BLOCK by default, that might
    not be the best fit if we know that this callsite is guaranteed to block.
  - The ScopedBlockingCall's scope covers the entirety of the blocking operation
    previously asserted against by the AssertBlockingAllowed().
  - Calls to blocking //base APIs don't need to be annotated
    with ScopedBlockingCall. All blocking //base APIs (e.g. base::ReadFileToString, base::File::Read,
    base::SysInfo::AmountOfFreeDiskSpace, base::WaitableEvent::Wait, etc.) have their
    own internal annotations.

Refer to the top-level CL if necessary :
https://chromium-review.googlesource.com/c/chromium/src/+/1338391

Please CQ if LGTY!

This CL was uploaded by git cl split.

R=jennyz@chromium.org

Bug: 903957
Change-Id: Idc81701192f6879ee7e11e2f15e89292d9406f9e
Reviewed-on: https://chromium-review.googlesource.com/c/1338414
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608915}

chrome/browser/ui/app_list/search/search_result_ranker/app_search_result_ranker.cc

@@ -10,6 +10,7 @@
 #include "base/task/post_task.h"
 #include "base/task/task_traits.h"
 #include "base/task_runner_util.h"
+#include "base/threading/scoped_blocking_call.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/app_list/search/search_result_ranker/app_launch_predictor.h"
 #include "chrome/browser/ui/app_list/search/search_result_ranker/app_launch_predictor.pb.h"
@@ -41,7 +42,7 @@ std::unique_ptr<AppLaunchPredictor> CreatePredictor(
 // Save |proto| to |predictor_filename|.
 void SaveToDiskOnWorkerThread(const base::FilePath& predictor_filename,
                               const AppLaunchPredictorProto& proto) {
-  base::AssertBlockingAllowedDeprecated();
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
 
   std::string proto_str;
   if (!proto.SerializeToString(&proto_str))
@@ -55,7 +56,7 @@ void SaveToDiskOnWorkerThread(const base::FilePath& predictor_filename,
 std::unique_ptr<AppLaunchPredictor> LoadPredictorFromDiskOnWorkerThread(
     const base::FilePath& predictor_filename,
     const std::string predictor_name) {
-  base::AssertBlockingAllowedDeprecated();
+  base::ScopedBlockingCall scoped_blocking_call(base::BlockingType::MAY_BLOCK);
 
   // Loads proto string from local disk.
   std::string proto_str;