[WebRTC] Implement Windows ScreenDrawer to test ScreenCapturer*

webrtc/modules/desktop_capture/screen_drawer_unittest.cc

+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#include "webrtc/modules/desktop_capture/screen_drawer.h"
+
+#include <stdint.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/base/random.h"
+#include "webrtc/base/timeutils.h"
+#include "webrtc/system_wrappers/include/sleep.h"
+
+namespace webrtc {
+
+// These are a set of manual test cases, as we do not have an automatical way to
+// detect whether a ScreenDrawer on a certain platform works well without
+// ScreenCapturer(s). So you may execute these test cases with
+// --gtest_also_run_disabled_tests --gtest_filter=ScreenDrawerTest.*.
+TEST(ScreenDrawerTest, DISABLED_DrawRectangles) {
+  std::unique_ptr<ScreenDrawer> drawer = ScreenDrawer::Create();
+  if (!drawer) {
+    // No ScreenDrawer implementation for current platform.
+    return;
+  }
+
+  drawer->Clear();
+  DesktopRect rect = drawer->DrawableRegion();
+  Random random(rtc::TimeMicros());
+  for (int i = 0; i < 100; i++) {
+    // Make sure we at least draw one pixel.
+    int left = random.Rand(rect.left(), rect.right() - 2);
+    int top = random.Rand(rect.top(), rect.bottom() - 2);
+    drawer->DrawRectangle(
+        DesktopRect::MakeLTRB(left, top, random.Rand(left + 1, rect.right()),
+                              random.Rand(top + 1, rect.bottom())),
+        random.Rand<uint32_t>());
+
+    if (i == 50) {
+      SleepMs(10000);
+      drawer->Clear();
+    }
+  }
+
+  SleepMs(10000);
+  drawer->Clear();
+}
+
+}  // namespace webrtc