Allow CopyFromBackingStore to fallback to copying from the renderer side if the accelerated surface…

content/browser/renderer_host/media/web_contents_video_capture_device.cc

Index: content/browser/renderer_host/media/web_contents_video_capture_device.cc
diff --git a/content/browser/renderer_host/media/web_contents_video_capture_device.cc b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
index 66385265dae28634c4b804d87307e29e5eec0aa8..637dd1db85ae00b2cf8c3a5a685b05cb9b1263eb 100644
--- a/content/browser/renderer_host/media/web_contents_video_capture_device.cc
+++ b/content/browser/renderer_host/media/web_contents_video_capture_device.cc
@@ -989,7 +989,15 @@ void BackingStoreCopier::StartCopy(
   TRACE_EVENT_ASYNC_BEGIN1("mirroring", "Capture", this,
                            "frame_number", frame_number);
 
-  if (view && view->CanCopyToVideoFrame()) {
+  if (!view->IsSurfaceAvailableForCopy()) {
+    // Fallback to the more expensive renderer-side copy if the surface and
+    // backing store are not accessible.
+    rwh->GetSnapshotFromRenderer(
+        gfx::Rect(),
+        base::Bind(&BackingStoreCopier::DidCopyFromBackingStore,
+                   base::Unretained(this), frame_number,
+                   base::Time::Now(), callback));
+  } else if (view && view->CanCopyToVideoFrame()) {
     gfx::Size view_size = view->GetViewBounds().size();
 
     view->CopyFromCompositingSurfaceToVideoFrame(