Change other usages of .size() to .empty() when applicable.

chrome/browser/sync/profile_sync_service_unittest.cc

 // Copyright (c) 2010 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 <stack>
 #include <vector>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "base/file_util.h"
 #include "base/message_loop.h"
@@ skipping 253 matching lines @@
 
   const vector<sync_api::SyncManager::ChangeRecord>& changes() {
     return changes_;
   }
 
  private:
   // Helper function to push an ACTION_UPDATE record onto the back
   // of the changelist.
   void SetModified(int64 id) {
     // Coalesce multi-property edits.
-    if (changes_.size() > 0 && changes_.back().id == id &&
+    if (!changes_.empty() && changes_.back().id == id &&
         changes_.back().action ==
         sync_api::SyncManager::ChangeRecord::ACTION_UPDATE)
       return;
     sync_api::SyncManager::ChangeRecord record;
     record.action = sync_api::SyncManager::ChangeRecord::ACTION_UPDATE;
     record.id = id;
     changes_.push_back(record);
   }
 
   // The transaction on which everything happens.
@@ skipping 1374 matching lines @@
   // This file should have been deleted when the whole directory was nuked.
   ASSERT_FALSE(file_util::PathExists(sync_file3));
   ASSERT_FALSE(file_util::PathExists(sync_file1));
 
   // This will still exist, but the text should have changed.
   ASSERT_TRUE(file_util::PathExists(sync_file2));
   std::string file2text;
   file_util::ReadFileToString(sync_file2, &file2text);
   ASSERT_FALSE(file2text.compare(nonsense2) == 0);
 }