Add DesktopFrame rotation functions

webrtc/modules/desktop_capture/test_utils.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/test_utils.h"
+
+#include <string.h>
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+void ClearDesktopFrame(DesktopFrame* frame) {
+  RTC_DCHECK(frame);
+  memset(frame->data(), 0, frame->stride() * frame->size().height());

[Sergey Ulanov, 2016/11/22 20:33:07]

stride() may be negative (see
https://codesearch.chromium.org/chromium/src/third_party/webrtc/modules/deskt...
). This code won't work correctly in that case.

[Hzj_jie, 2016/11/22 21:56:02]

Yes, I noticed this class before. Since ClearDesktopFrame does not take care of
this specific implementation, I did not consider it.

The InvertDesktopFrame looks weird, is it because of some specific API
limitations in MAC?

I have updated the logic.

+}
+
+bool DesktopFrameDataEquals(const DesktopFrame& left,
+                            const DesktopFrame& right) {
+  if (!left.size().equals(right.size())) {
+    return false;
+  }
+  if (left.stride() == right.stride() &&
+      left.stride() == DesktopFrame::kBytesPerPixel * left.size().width()) {

[Sergey Ulanov, 2016/11/22 20:33:07]

I don't think you need this optimization, especially given that this is a
test-only code.

[Hzj_jie, 2016/11/22 21:56:02]

Done.

+    return memcmp(left.data(),
+                  right.data(),
+                  left.stride() * left.size().height()) == 0;
+  }
+
+  const uint8_t* my_array = left.data();

[Sergey Ulanov, 2016/11/22 20:33:07]

s/my/left/?

[Hzj_jie, 2016/11/22 21:56:02]

Done.

+  const uint8_t* right_array = right.data();
+  for (int i = 0; i < left.size().height(); i++) {
+    if (memcmp(my_array,
+               right_array,
+               DesktopFrame::kBytesPerPixel * left.size().width()) != 0) {
+      return false;
+    }
+    my_array += left.stride();
+    right_array += right.stride();
+  }
+
+  return true;
+}
+
+}  // namespace webrtc