Connect to DesktopEnvironment's stubs only when audio/video schedulers are about to be created.

remoting/capturer/video_frame_capturer_fake.cc

Index: remoting/capturer/video_frame_capturer_fake.cc
diff --git a/remoting/capturer/video_frame_capturer_fake.cc b/remoting/capturer/video_frame_capturer_fake.cc
index a27e62cf1aea85804862322076bb6e24ba33d1b7..7c25432f13c2c0302fc11019381afe5e8370ac53 100644
--- a/remoting/capturer/video_frame_capturer_fake.cc
+++ b/remoting/capturer/video_frame_capturer_fake.cc
@@ -12,8 +12,8 @@ namespace remoting {
 // VideoFrameCapturerFake generates a white picture of size kWidth x kHeight
 // with a rectangle of size kBoxWidth x kBoxHeight. The rectangle moves kSpeed
 // pixels per frame along both axes, and bounces off the sides of the screen.
-static const int kWidth = 800;
-static const int kHeight = 600;
+static const int kWidth = VideoFrameCapturerFake::kWidth;
+static const int kHeight = VideoFrameCapturerFake::kHeight;
 static const int kBoxWidth = 140;
 static const int kBoxHeight = 140;
 static const int kSpeed = 20;