Forward capturer_id between DesktopFrame and its implementations

This is a trivial change to forward capturer id from various DesktopFrame
related implementations.

BUG=chromium:679523, chromium:650926

Review-Url: https://codereview.webrtc.org/2851513003
Cr-Commit-Position: refs/heads/master@{#17918}
diff --git a/webrtc/modules/desktop_capture/desktop_and_cursor_composer.cc b/webrtc/modules/desktop_capture/desktop_and_cursor_composer.cc
index f5b85e4..d9d4b12 100644
--- a/webrtc/modules/desktop_capture/desktop_and_cursor_composer.cc
+++ b/webrtc/modules/desktop_capture/desktop_and_cursor_composer.cc
@@ -81,6 +81,7 @@
                    frame->shared_memory()) {
   set_dpi(frame->dpi());
   set_capture_time_ms(frame->capture_time_ms());
+  set_capturer_id(frame->capturer_id());
   mutable_updated_region()->Swap(frame->mutable_updated_region());
   original_frame_ = std::move(frame);
 
diff --git a/webrtc/modules/desktop_capture/desktop_capturer_differ_wrapper.cc b/webrtc/modules/desktop_capture/desktop_capturer_differ_wrapper.cc
index 1ad9ce4..196a987 100644
--- a/webrtc/modules/desktop_capture/desktop_capturer_differ_wrapper.cc
+++ b/webrtc/modules/desktop_capture/desktop_capturer_differ_wrapper.cc
@@ -214,6 +214,7 @@
   frame->set_capture_time_ms(frame->GetUnderlyingFrame()->capture_time_ms() +
                              (rtc::TimeNanos() - start_time_nanos) /
                                  rtc::kNumNanosecsPerMillisec);
+  frame->set_capturer_id(frame->GetUnderlyingFrame()->capturer_id());
   callback_->OnCaptureResult(result, std::move(frame));
 }
 
diff --git a/webrtc/modules/desktop_capture/desktop_frame.cc b/webrtc/modules/desktop_capture/desktop_frame.cc
index 12e4ed8..1c3939b 100644
--- a/webrtc/modules/desktop_capture/desktop_frame.cc
+++ b/webrtc/modules/desktop_capture/desktop_frame.cc
@@ -76,6 +76,7 @@
   }
   result->set_dpi(frame.dpi());
   result->set_capture_time_ms(frame.capture_time_ms());
+  result->set_capturer_id(frame.capturer_id());
   *result->mutable_updated_region() = frame.updated_region();
   return result;
 }