Prevent upscaling in desktop capture.

The previous CL landed (r238359) is missing a size check to prevent upscaling
in desktop capture. The correct logic should be to use native resolution
if both maxWidth and maxHeight are no smaller than source dimensions, and
to compute letterbox region if otherwise.

BUG=324923
TEST=trybot, Chrome OS feedback screen captures in native resolution
R=sergeyu@chromium.org
TBR=wjia@chromium.org

Review URL: https://codereview.chromium.org/103253003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238514 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/media/video_capture_device_impl.cc

@@ -138,10 +138,16 @@ void ThreadSafeCaptureOracle::UpdateCaptureSize(const gfx::Size& source_size) {
   if (!capture_size_updated_ || params_.allow_resolution_change) {
     // The capture resolution should not exceed the source frame size.
     // In other words it should downscale the image but not upscale it.
+    if (source_size.width() > params_.requested_format.frame_size.width() ||
+        source_size.height() > params_.requested_format.frame_size.height()) {
       gfx::Rect capture_rect = media::ComputeLetterboxRegion(
           gfx::Rect(params_.requested_format.frame_size), source_size);
       capture_size_ = gfx::Size(MakeEven(capture_rect.width()),
                                 MakeEven(capture_rect.height()));
+    } else {
+      capture_size_ = gfx::Size(MakeEven(source_size.width()),
+                                MakeEven(source_size.height()));
+    }
     capture_size_updated_ = true;
   }
 }