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

chrome/browser/ui/cocoa/cocoa_test_helper.mm

 // Copyright (c) 2009 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.
 
 #import "chrome/browser/ui/cocoa/cocoa_test_helper.h"
 
 #include "base/debug/debugger.h"
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
 #include "base/test/test_timeouts.h"
@@ skipping 93 matching lines @@
   // one to two spins through the event loop to see a change.
 
   // NOTE(shess): Under valgrind, -nextEventMatchingMask:* in one test
   // needed to run twice, once taking .2 seconds, the next time .6
   // seconds.  The loop exit condition attempts to be scalable.
 
   // Get the set of windows which weren't present when the test
   // started.
   std::set<NSWindow*> windows_left(WindowsLeft());
 
-  while (windows_left.size() > 0) {
+  while (!windows_left.empty()) {
     // Cover delayed actions by spinning the loop at least once after
     // this timeout.
     const NSTimeInterval kCloseTimeoutSeconds =
         TestTimeouts::action_timeout_ms() / 1000.0;
 
     // Cover chains of delayed actions by spinning the loop at least
     // this many times.
     const int kCloseSpins = 3;
 
     // Track the set of remaining windows so that everything can be
@@ skipping 73 matching lines @@
   if (!test_window_) {
     test_window_ = [[CocoaTestHelperWindow alloc] init];
     if (base::debug::BeingDebugged()) {
       [test_window_ orderFront:nil];
     } else {
       [test_window_ orderBack:nil];
     }
   }
   return test_window_;
 }