Fix several uses of ScopedTempDir in components_unittests.

components/precache/core/precache_database_unittest.cc

 // Copyright 2013 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/precache/core/precache_database.h"
 
 #include <map>
 
 #include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
@@ skipping 77 matching lines @@
                               int host_rank);
   void RecordFetchFromNetworkCellular(const GURL& url,
                                       base::TimeDelta latency,
                                       const base::Time& fetch_time,
                                       int64 size);
   void RecordFetchFromCache(const GURL& url, const base::Time& fetch_time,
                             int64 size);
   void RecordFetchFromCacheCellular(const GURL& url,
                                     const base::Time& fetch_time, int64 size);
 
+  // Must be declared first so that it is destroyed last.
+  base::ScopedTempDir scoped_temp_dir_;
+
   // Having this MessageLoop member variable causes base::MessageLoop::current()
   // to be set properly.
   base::MessageLoopForUI loop_;
 
   scoped_refptr<PrecacheDatabase> precache_database_;
-  base::ScopedTempDir scoped_temp_dir_;
   base::HistogramTester histograms_;
   base::HistogramTester::CountsMap expected_histogram_counts_;
 
   void ExpectNewSample(const std::string& histogram_name,
                        base::HistogramBase::Sample sample) {
     histograms_.ExpectUniqueSample(histogram_name, sample, 1);
     expected_histogram_counts_[histogram_name]++;
   }
 
   void ExpectNoOtherSamples() {
@@ skipping 253 matching lines @@
   EXPECT_THAT(histograms_.GetAllSamples("Precache.Saved"),
               ElementsAre(Bucket(kSize1, 1), Bucket(kSize3, 1)));
 
   EXPECT_THAT(histograms_.GetAllSamples("Precache.Saved.Cellular"),
               ElementsAre(Bucket(kSize1, 1)));
 }
 
 }  // namespace
 
 }  // namespace precache