Prevent upscaling in desktop capture.

content/browser/renderer_host/media/video_capture_device_impl.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/media/video_capture_device_impl.h"
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/callback_forward.h"
 #include "base/callback_helpers.h"
@@ skipping 120 matching lines @@
 
 void ThreadSafeCaptureOracle::UpdateCaptureSize(const gfx::Size& source_size) {
   base::AutoLock guard(lock_);
 
   // If this is the first call to UpdateCaptureSize(), or the receiver supports
   // variable resolution, then determine the capture size by treating the
   // requested width and height as maxima.
   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.
-    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()));
+    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;
   }
 }
 
 void ThreadSafeCaptureOracle::Stop() {
   base::AutoLock guard(lock_);
   client_.reset();
 }
 
 void ThreadSafeCaptureOracle::ReportError() {
@@ skipping 134 matching lines @@
     return;
 
   if (oracle_proxy_)
     oracle_proxy_->ReportError();
 
   StopAndDeAllocate();
   TransitionStateTo(kError);
 }
 
 }  // namespace content