Modify ScreenCaptureFrameQueue into a template

webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc

Index: webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc
diff --git a/webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc b/webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc
index d3035a15ca52d4c3f79aa2082c0dc4610e97f9ea..1171388333edf947b857fc31c035e1be00bc6490 100644
--- a/webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc
+++ b/webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc
@@ -14,6 +14,7 @@
 
 #include <utility>
 
+#include "webrtc/base/checks.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_frame_win.h"
@@ -97,7 +98,8 @@ void ScreenCapturerWinGdi::SetSharedMemoryFactory(
 void ScreenCapturerWinGdi::Capture(const DesktopRegion& region) {
   TickTime capture_start_time = TickTime::Now();
 
-  queue_.MoveToNextFrame();
+  queue_.MoveToNext();
+  RTC_DCHECK(!queue_.current() || !queue_.current()->IsShared());
 
   // Request that the system not power-down the system, or the display hardware.
   if (!SetThreadExecutionState(ES_DISPLAY_REQUIRED | ES_SYSTEM_REQUIRED)) {
@@ -116,8 +118,8 @@ void ScreenCapturerWinGdi::Capture(const DesktopRegion& region) {
     return;
   }
 
-  const DesktopFrame* current_frame = queue_.current_frame();
-  const DesktopFrame* last_frame = queue_.previous_frame();
+  const DesktopFrame* current_frame = queue_.current();
+  const DesktopFrame* last_frame = queue_.previous();
   if (last_frame && last_frame->size().equals(current_frame->size())) {
     // Make sure the differencer is set up correctly for these previous and
     // current screens.
@@ -145,7 +147,7 @@ void ScreenCapturerWinGdi::Capture(const DesktopRegion& region) {
   helper_.set_size_most_recent(current_frame->size());
 
   // Emit the current frame.
-  DesktopFrame* frame = queue_.current_frame()->Share();
+  DesktopFrame* frame = queue_.current()->Share();
   frame->set_dpi(DesktopVector(
       GetDeviceCaps(desktop_dc_, LOGPIXELSX),
       GetDeviceCaps(desktop_dc_, LOGPIXELSY)));
@@ -258,22 +260,22 @@ bool ScreenCapturerWinGdi::CaptureImage() {
   // If the current buffer is from an older generation then allocate a new one.
   // Note that we can't reallocate other buffers at this point, since the caller
   // may still be reading from them.
-  if (!queue_.current_frame() ||
-      !queue_.current_frame()->size().equals(screen_rect.size())) {
+  if (!queue_.current() ||
+      !queue_.current()->size().equals(screen_rect.size())) {
     assert(desktop_dc_ != NULL);
     assert(memory_dc_ != NULL);
 
     std::unique_ptr<DesktopFrame> buffer(DesktopFrameWin::Create(
         size, shared_memory_factory_.get(), desktop_dc_));
-    if (!buffer.get())
+    if (!buffer)
       return false;
-    queue_.ReplaceCurrentFrame(buffer.release());
+    queue_.ReplaceCurrent(SharedDesktopFrame::Wrap(std::move(buffer)));
   }
 
   // Select the target bitmap into the memory dc and copy the rect from desktop
   // to memory.
   DesktopFrameWin* current = static_cast<DesktopFrameWin*>(
-      queue_.current_frame()->GetUnderlyingFrame());
+      queue_.current()->GetUnderlyingFrame());
   HGDIOBJ previous_object = SelectObject(memory_dc_, current->bitmap());
   if (previous_object != NULL) {
     BitBlt(memory_dc_,