WebRtc Win Desktop capture: ignore Win8+ Modern Apps' windows.

webrtc/modules/desktop_capture/window_capturer_win.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 41 matching lines @@
   const size_t kTitleLength = 500;
   WCHAR window_title[kTitleLength];
   // Truncate the title if it's longer than kTitleLength.
   GetWindowText(hwnd, window_title, kTitleLength);
   window.title = rtc::ToUtf8(window_title);
 
   // Skip windows when we failed to convert the title or it is empty.
   if (window.title.empty())
     return TRUE;
 
+  // Filter out windows modern apps' windows based on the observation:
+  // When a modern app's window is in foreground and not minimized :
+  // class name = ApplicationFrameWindow
+  // When a modern app's window is in foreground and minimized :
+  // class name = windows.UI.Core.coreWindow
+  // when a modern app's window is in background:
+  // It is listed as two windows with class name = ApplicationFrameWindow
+  // and class name = windows.UI.Core.coreWindow.
+  // Webrtc is not able to capture modern apps' windows on 09/30/2015.

[mcasas, 2015/10/01 17:19:04]

This is a bit too verbose :) Please rephrase more succintly
and with a view on the purpose, i.e. "Windows X cannot
capture windows of type Y; those are identified by Z and W".

What's "modern" referring to? If there is a bug associated
to this peculiar situation, mention it like http://crbug.com/bla.

[gyzhou, 2015/10/02 18:30:34]

Done.

+  if (rtc::IsWindows8OrLater()) {
+    char clsName[1024];

[mcasas, 2015/10/01 17:19:04]

This needs to be WCHAR right? Like in l.53.

[gyzhou, 2015/10/02 18:30:34]

GetClassName using WCHAR as input
GetClassNameA can use char as input

+    GetClassNameA(hwnd, clsName, 1024);

[mcasas, 2015/10/01 17:19:04]

What about the return value? and what is 1024? 
Sugggestion: 

const size_t kMaxNameLength = 1024u;
std::wstring clsName(kMaxNameLength);
const int class_name_length = GetClassNAmeA(hwnd, clsName.data(),
kMaxNameLength);
RTC_DCHECK(class_name_length) << "Error retrieving the application's class
name";
if (clsName == "ApplicationFrameWindow" ||
    clsName == "Windows.UI.CoreWindow)) {
  return TRUE;
}

(Mind the  {}, needed if either condition or body are longer than
a line).

(Mind TRUE versus |true|).

[gyzhou, 2015/10/02 18:30:34]

Done.

+    if (strcmp(clsName, "ApplicationFrameWindow") == 0 ||
+        strcmp(clsName, "Windows.UI.Core.CoreWindow") == 0)

[mcasas, 2015/10/01 17:19:04]

Nit: I wouldn't use camlcase names ever, but if that's 
the style of the file/folder, then so be it. Rename my
variables accordingly above if this is the case.

[gyzhou, 2015/10/02 18:30:34]

Done.

+      return true;
+  }
+
   list->push_back(window);
 
   return TRUE;
 }
 
 class WindowCapturerWin : public WindowCapturer {
  public:
   WindowCapturerWin();
   virtual ~WindowCapturerWin();
 
@@ skipping 162 matching lines @@
 }
 
 }  // namespace
 
 // static
 WindowCapturer* WindowCapturer::Create(const DesktopCaptureOptions& options) {
   return new WindowCapturerWin();
 }
 
 }  // namespace webrtc