[refactor] add namespace 'crossdesk' to codebase

src/screen_capturer/screen_capturer.h

@@ -11,6 +11,8 @@
 
 #include "display_info.h"
 
+namespace crossdesk {
+
 class ScreenCapturer {
  public:
   typedef std::function<void(unsigned char*, int, int, int, const char*)>
@@ -30,5 +32,5 @@ class ScreenCapturer {
   virtual std::vector<DisplayInfo> GetDisplayInfoList() = 0;
   virtual int SwitchTo(int monitor_index) = 0;
 };
-
+}  // namespace crossdesk
 #endif