Add DesktopCapturerId and attach it to DesktopFrame

This change adds a DesktopCapturerId namespace, and attaches an int to each
DesktopFrame. ScreenCapturerWinGdi and ScreenCapturerWinDirectx now actively set
this field to differentiate themselves.

BUG=679523, 650926

Review-Url: https://codereview.webrtc.org/2759493002
Cr-Original-Commit-Position: refs/heads/master@{#17329}
Committed: 41e3d9ff3b
Review-Url: https://codereview.webrtc.org/2759493002
Cr-Commit-Position: refs/heads/master@{#17347}

webrtc/modules/desktop_capture/desktop_capture_types.h

@@ -36,6 +36,34 @@ const ScreenId kFullDesktopScreenId = -1;
 
 const ScreenId kInvalidScreenId = -2;
 
+// Depends on webrtc/media:rtc_media_base will trigger a build break in
+// Chromium (Refer to https://codereview.chromium.org/2759493002/). The root
+// cause is still unclear. Before the root cause has been found, copy-paste the
+// definition of the FOURCC() macro here is a simple choice.
+
+/**** Copy from webrtc/media/base/videocommon.h ****/
+// Convert four characters to a FourCC code.
+// Needs to be a macro otherwise the OS X compiler complains when the kFormat*
+// constants are used in a switch.
+#define FOURCC(a, b, c, d)                                        \
+  ((static_cast<uint32_t>(a)) | (static_cast<uint32_t>(b) << 8) | \
+   (static_cast<uint32_t>(c) << 16) | (static_cast<uint32_t>(d) << 24))
+// Some pages discussing FourCC codes:
+//   http://www.fourcc.org/yuv.php
+//   http://v4l2spec.bytesex.org/spec/book1.htm
+//   http://developer.apple.com/quicktime/icefloe/dispatch020.html
+//   http://msdn.microsoft.com/library/windows/desktop/dd206750.aspx#nv12
+//   http://people.xiph.org/~xiphmont/containers/nut/nut4cc.txt
+/**** End copy from webrtc/media/base/videocommon.h ****/
+
+// An integer to attach to each DesktopFrame to differentiate the generator of
+// the frame.
+namespace DesktopCapturerId {
+  constexpr uint32_t kUnknown = 0;
+  constexpr uint32_t kScreenCapturerWinGdi = FOURCC('G', 'D', 'I', ' ');
+  constexpr uint32_t kScreenCapturerWinDirectx = FOURCC('D', 'X', 'G', 'I');
+}  // namespace DesktopCapturerId
+
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_DESKTOP_CAPTURE_DESKTOP_CAPTURE_TYPES_H_

webrtc/modules/desktop_capture/desktop_frame.cc

@@ -26,8 +26,8 @@ DesktopFrame::DesktopFrame(DesktopSize size,
       shared_memory_(shared_memory),
       size_(size),
       stride_(stride),
-      capture_time_ms_(0) {
-}
+      capture_time_ms_(0),
+      capturer_id_(DesktopCapturerId::kUnknown) {}
 
 DesktopFrame::~DesktopFrame() {}
 

webrtc/modules/desktop_capture/desktop_frame.h

@@ -14,6 +14,7 @@
 #include <memory>
 
 #include "webrtc/base/constructormagic.h"
+#include "webrtc/modules/desktop_capture/desktop_capture_types.h"
 #include "webrtc/modules/desktop_capture/desktop_geometry.h"
 #include "webrtc/modules/desktop_capture/desktop_region.h"
 #include "webrtc/modules/desktop_capture/shared_memory.h"
@@ -68,6 +69,14 @@ class DesktopFrame {
   // A helper to return the data pointer of a frame at the specified position.
   uint8_t* GetFrameDataAtPos(const DesktopVector& pos) const;
 
+  // The DesktopCapturer implementation which generates current DesktopFrame.
+  // Not all DesktopCapturer implementations set this field; it's set to
+  // kUnknown by default.
+  uint32_t capturer_id() const { return capturer_id_; }
+  void set_capturer_id(uint32_t capturer_id) {
+    capturer_id_ = capturer_id;
+  }
+
  protected:
   DesktopFrame(DesktopSize size,
                int stride,
@@ -87,6 +96,7 @@ class DesktopFrame {
   DesktopRegion updated_region_;
   DesktopVector dpi_;
   int64_t capture_time_ms_;
+  uint32_t capturer_id_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(DesktopFrame);
 };

webrtc/modules/desktop_capture/win/screen_capturer_win_directx.cc

@@ -137,6 +137,7 @@ void ScreenCapturerWinDirectx::CaptureFrame() {
   result->set_capture_time_ms(
       (rtc::TimeNanos() - capture_start_time_nanos) /
       rtc::kNumNanosecsPerMillisec);
+  result->set_capturer_id(DesktopCapturerId::kScreenCapturerWinDirectx);
   callback_->OnCaptureResult(Result::SUCCESS, std::move(result));
 }
 

webrtc/modules/desktop_capture/win/screen_capturer_win_gdi.cc

@@ -94,6 +94,7 @@ void ScreenCapturerWinGdi::CaptureFrame() {
   frame->set_capture_time_ms(
       (rtc::TimeNanos() - capture_start_time_nanos) /
       rtc::kNumNanosecsPerMillisec);
+  frame->set_capturer_id(DesktopCapturerId::kScreenCapturerWinGdi);
   callback_->OnCaptureResult(Result::SUCCESS, std::move(frame));
 }