Finally rip the global StackingClient bandaid off.

- Removes the aura::client::SetStackingClient(StackingClient*) interface.
- Moves the ash StackingController from a singleton owned by ash::Shell to one StackingController per RootWindow owned by the ash::RootWindowController. (Also removes a spurious delegate method, where every implementation creates the same object, including tests.)
- Removes the global DesktopStackingClient and related interfaces.
- Fix the ChromeViewsDelegate so that it still sets context in chromeos builds.
- Rename content::ShellStackingClientAsh to content::MinimalAsh to reflect what it really does.

In addition, the following fix ups apply:

- Previously, WebContentsViewAura asserted that it needed a context window. Now if no context window is provided, it isn't added to an aura hierarchy. There are times when that context doesn't exist: various chromeos dialogs that directly invoke WebView and toplevel extension/app windows that are created from background pages that don't have contexts.
- Because of that, added a few of NULL checking to RenderWidgetHostViewAura. (Other methods NULL checked Window::GetRootWindow(), but there were a few that didn't and relied on the old NULL means lookup in the StackingClient behaviour.)

BUG=161882

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=177182

Review URL: https://codereview.chromium.org/11829040

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@178083 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 7 insertions, 0 deletions

diff --git a/ui/gfx/screen_win.cc b/ui/gfx/screen_win.cc
index 9b33c6b..80614a4 100644
--- a/ui/gfx/screen_win.cc
+++ b/ui/gfx/screen_win.cc
@@ -57,6 +57,13 @@ int ScreenWin::GetNumDisplays() {
 
 gfx::Display ScreenWin::GetDisplayNearestWindow(gfx::NativeView window) const {
   HWND window_hwnd = GetHWNDFromNativeView(window);
+  if (!window_hwnd) {
+    // When |window| isn't rooted to a display, we should just return the
+    // default display so we get some correct display information like the
+    // scaling factor.
+    return GetPrimaryDisplay();
+  }
+
   MONITORINFO monitor_info;
   monitor_info.cbSize = sizeof(monitor_info);
   GetMonitorInfo(MonitorFromWindow(window_hwnd, MONITOR_DEFAULTTONEAREST),