overscroll: Take a screenshot at more appropriate times.

content/renderer/render_view_impl.cc

 // Copyright (c) 2012 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/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/bind.h"
@@ skipping 5429 matching lines @@
     // different process.  This involves running the unload handler and clearing
     // the page.  Once WasSwappedOut is called, we also allow this process to
     // exit if there are no other active RenderViews in it.
 
     // Send an UpdateState message before we get swapped out.
     SyncNavigationState();
 
     // Synchronously run the unload handler before sending the ACK.
     webview()->dispatchUnloadEvent();
 
+    // Mark the view as hidden, to make sure that it does not erase the paint
+    // contents.
+    SetHidden(true);

[Charlie Reis, 2013/01/09 00:49:23]

Interesting.  This looks similar to the setVisibilityState call below.  I wonder
if we should move that call up alongside this one, and whether both are needed
or if just moving that up here is sufficient.

[sadrul, 2013/01/09 17:44:19]

I moved the call to setVisibilityState up here.

SetHidden() and setVisibilityState() do different things, and both are called in
response to a WasHidden/WasShown message from the browser. I tried removing the
call to SetHidden, but that didn't work.

Do you think it might be necessary to call SetHidden(false) when the renderer
gets swapped back in, or does it always get a WasShown message when necessary?

+
     // Swap out and stop sending any IPC messages that are not ACKs.
     SetSwappedOut(true);
 
     // Replace the page with a blank dummy URL. The unload handler will not be
     // run a second time, thanks to a check in FrameLoader::stopLoading.
     // TODO(creis): Need to add a better way to do this that avoids running the
     // beforeunload handler. For now, we just run it a second time silently.
     NavigateToSwappedOutURL(webview()->mainFrame());
 
     // Let WebKit know that this view is hidden so it can drop resources and
@@ skipping 1046 matching lines @@
 }
 #endif
 
 void RenderViewImpl::OnReleaseDisambiguationPopupDIB(
     TransportDIB::Handle dib_handle) {
   TransportDIB* dib = TransportDIB::CreateWithHandle(dib_handle);
   RenderProcess::current()->ReleaseTransportDIB(dib);
 }
 
 }  // namespace content