[Chromoting] Do not post updated host configuration unless the configuration has actually changed.

remoting/host/config_file_watcher.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.
 
 #include "remoting/host/config_file_watcher.h"
 
+#include <string>
+
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/files/file_path_watcher.h"
 #include "base/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/timer.h"
 
 namespace remoting {
@@ skipping 26 matching lines @@
   virtual ~ConfigFileWatcherImpl();
 
   void FinishStopping();
 
   // Called every time the host configuration file is updated.
   void OnConfigUpdated(const FilePath& path, bool error);
 
   // Reads the configuration file and passes it to the delegate.
   void ReloadConfig();
 
+  std::string config_;
   FilePath config_path_;
 
   scoped_ptr<base::DelayTimer<ConfigFileWatcherImpl> > config_updated_timer_;
 
   // Monitors the host configuration file.
   scoped_ptr<base::files::FilePathWatcher> config_watcher_;
 
   base::WeakPtrFactory<ConfigFileWatcher::Delegate> delegate_weak_factory_;
   base::WeakPtr<ConfigFileWatcher::Delegate> delegate_;
 
@@ skipping 107 matching lines @@
   std::string config;
   if (!file_util::ReadFileToString(config_path_, &config)) {
     LOG(ERROR) << "Failed to read '" << config_path_.value() << "'";
     main_task_runner_->PostTask(
         FROM_HERE,
         base::Bind(&ConfigFileWatcher::Delegate::OnConfigWatcherError,
                    delegate_));
     return;
   }
 
-  main_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&ConfigFileWatcher::Delegate::OnConfigUpdated, delegate_,
-                 config));
+  // Post an updated configuration only if it has actually changed.
+  if (config_ != config) {
+    config_ = config;
+    main_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&ConfigFileWatcher::Delegate::OnConfigUpdated, delegate_,
+                   config_));
+  }
 }
 
 }  // namespace remoting