[Cleanup] Migrate the FileMetricsProvider to use the Task Scheduler.

components/metrics/file_metrics_provider_unittest.cc

 // Copyright 2016 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 "components/metrics/file_metrics_provider.h"
 
 #include <functional>
 
 #include "base/files/file_util.h"
 #include "base/files/memory_mapped_file.h"
@@ skipping 69 matching lines @@
 
   FileMetricsProviderTest()
       : create_large_files_(GetParam()),
         task_runner_(new base::TestSimpleTaskRunner()),
         thread_task_runner_handle_(task_runner_),
         statistics_recorder_(
             base::StatisticsRecorder::CreateTemporaryForTesting()),
         prefs_(new TestingPrefServiceSimple) {
     EXPECT_TRUE(temp_dir_.CreateUniqueTempDir());
     FileMetricsProvider::RegisterPrefs(prefs_->registry(), kMetricsName);
+    FileMetricsProvider::SetTaskRunnerForTesting(task_runner_);
   }
 
   ~FileMetricsProviderTest() override {
     // Clear out any final remaining tasks.
     task_runner_->RunUntilIdle();
     // If a global histogram allocator exists at this point then it likely
     // acquired histograms that will continue to point to the released
     // memory and potentially cause use-after-free memory corruption.
     DCHECK(!base::GlobalHistogramAllocator::Get());
   }
 
   TestingPrefServiceSimple* prefs() { return prefs_.get(); }
   base::FilePath temp_dir() { return temp_dir_.GetPath(); }
   base::FilePath metrics_file() {
     return temp_dir_.GetPath().AppendASCII(kMetricsFilename);
   }
 
   FileMetricsProvider* provider() {
     if (!provider_)
-      provider_.reset(new FileMetricsProvider(task_runner_, prefs()));
+      provider_.reset(new FileMetricsProvider(prefs()));
     return provider_.get();
   }
 
   void OnDidCreateMetricsLog() {
     provider()->OnDidCreateMetricsLog();
   }
 
   bool HasInitialStabilityMetrics() {
     return provider()->HasInitialStabilityMetrics();
   }
@@ skipping 471 matching lines @@
     EXPECT_TRUE(ProvideIndependentMetrics(&profile, &snapshot_manager));
     EXPECT_FALSE(ProvideIndependentMetrics(&profile, &snapshot_manager));
   }
   EXPECT_TRUE(base::PathExists(metrics_file()));
   OnDidCreateMetricsLog();
   RunTasks();
   EXPECT_FALSE(base::PathExists(metrics_file()));
 }
 
 }  // namespace metrics