Move ReadFileToString to the base namespace.

tools/android/device_stats_monitor/device_stats_monitor.cc

 // Copyright (c) 2012 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.
 
 // Dumps CPU and IO stats to a file at a regular interval.
 //
 // Output may be post processed by host to get top/iotop style information.
 
 #include <signal.h>
 #include <unistd.h>
@@ skipping 26 matching lines @@
   // Yes, this buffers everything in memory, so it cannot be used for extended
   // durations without OOM. But that beats writing during the trace which
   // would affect the results.
   void Start(int hz) {
     const int sample_interval = 1000000 / hz;
     const base::FilePath io_stats_path(kIOStatsPath);
     const base::FilePath cpu_stats_path(kCPUStatsPath);
     std::string out;
     while (record_) {
       out.clear();
-      CHECK(file_util::ReadFileToString(io_stats_path, &out));
-      CHECK(file_util::ReadFileToString(cpu_stats_path, &out));
+      CHECK(base::ReadFileToString(io_stats_path, &out));
+      CHECK(base::ReadFileToString(cpu_stats_path, &out));
       samples_.push_back(out);
       usleep(sample_interval);
     }
   }
 
   // Stops recording and saves samples to file.
   void StopAndDumpStats() {
     record_ = false;
     usleep(250 * 1000);
     std::ofstream out_stream;
@@ skipping 40 matching lines @@
       kDefaultHz;
 
   printf("Starting device stats monitor\n");
   g_device_stats_monitor = new DeviceStatsMonitor(args[0]);
   signal(SIGTERM, SigTermHandler);
   g_device_stats_monitor->Start(hz);
   delete g_device_stats_monitor;
 
   return 0;
 }