Merge 249763 "Fix the painting issue observed with windowed NPAP..."

> Fix the painting issue observed with windowed NPAPI Flash plugins when we switch away from a tab which has an instance of
> the plugin and switch back to it.
> 
> When we switch back to the tab with the plugin, the flash RVHWA window becomes visible. The code which runs in the visible notification
> handler runs through the plugin cutout rects calculation, which basically tries to remove areas where the plugin should not paint from its
> clip region. In this case the cutout rects comes out as empty and the clip region in the plugin window moves structure is NULL. We end up
> setting the window region to NULL which basically causes the plugin window to become useless.
> 
> Fix is to not mess with the window region of the plugin if the cutout rects are empty.
> 
> BUG=341564
> R=cpu@chromium.org, cpu
> TBR=jam
> 
> Review URL: https://codereview.chromium.org/140753008

TBR=ananta@chromium.org

Review URL: https://codereview.chromium.org/159113002

git-svn-id: svn://svn.chromium.org/chrome/branches/1750/src@250155 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 1 deletions

diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 7f4da87..4101a78 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -202,7 +202,10 @@ BOOL CALLBACK SetCutoutRectsCallback(HWND window, LPARAM param) {
       cutout_rects.push_back(offset_cutout);
     }
     gfx::SubtractRectanglesFromRegion(hrgn, cutout_rects);
-    SetWindowRgn(window, hrgn, TRUE);
+    // If we don't have any cutout rects then no point in messing with the
+    // window region.
+    if (cutout_rects.size())
+      SetWindowRgn(window, hrgn, TRUE);
   }
   return TRUE;
 }