Replace Atomic32 with webrtc/base/atomicops.h.

webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h

Index: webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h
diff --git a/webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h b/webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h
index bddc8099b25388402fb8a8f7e9abe7bb7ffccbf0..9f78eb1930df43c036f71d3edc58af26842f5ef6 100644
--- a/webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h
+++ b/webrtc/modules/desktop_capture/mac/full_screen_chrome_window_detector.h
@@ -13,8 +13,8 @@
 
 #include <ApplicationServices/ApplicationServices.h>
 
+#include "webrtc/base/atomicops.h"
 #include "webrtc/modules/desktop_capture/window_capturer.h"
-#include "webrtc/system_wrappers/interface/atomic32.h"
 #include "webrtc/system_wrappers/interface/tick_util.h"
 
 namespace webrtc {
@@ -34,9 +34,9 @@ class FullScreenChromeWindowDetector {
  public:
   FullScreenChromeWindowDetector();
 
-  void AddRef() { ++ref_count_; }
+  void AddRef() { rtc::AtomicOps::Increment(&ref_count_); }
   void Release() {
-    if (--ref_count_ == 0)
+    if (rtc::AtomicOps::Decrement(&ref_count_) == 0)
       delete this;
   }
 
@@ -51,7 +51,7 @@ class FullScreenChromeWindowDetector {
  private:
   ~FullScreenChromeWindowDetector();
 
-  Atomic32 ref_count_;
+  volatile int ref_count_;
 
   // We cache the last two results of the window list, so
   // |previous_window_list_| is taken at least 500ms before the next Capture()