aura: Try to make Linux host resize code more reliable.

ui/aura/desktop.h

Index: ui/aura/desktop.h
diff --git a/ui/aura/desktop.h b/ui/aura/desktop.h
index debf1d7007a6298d7a524e3388c0b777c9946b28..e6b6c971db1c42d6262c88c3882f1ba5581e30fd 100644
--- a/ui/aura/desktop.h
+++ b/ui/aura/desktop.h
@@ -56,6 +56,10 @@ class AURA_EXPORT Desktop : public ui::CompositorDelegate,
     return compositor_factory_;
   }
 
+  static void set_use_fullscreen_host_window(bool use_fullscreen) {
+    use_fullscreen_host_window_ = use_fullscreen;
+  }
+
   ui::Compositor* compositor() { return compositor_.get(); }
   gfx::Point last_mouse_location() const { return last_mouse_location_; }
   DesktopDelegate* delegate() { return delegate_.get(); }
@@ -167,12 +171,17 @@ class AURA_EXPORT Desktop : public ui::CompositorDelegate,
 
   static Desktop* instance_;
 
-  // Used to schedule painting.
-  base::WeakPtrFactory<Desktop> schedule_paint_factory_;
-
   // Factory used to create Compositors. Settable by tests.
   static ui::Compositor*(*compositor_factory_)();
 
+  // If set before the Desktop is created, the host window will cover the entire
+  // screen.  Note that this can still be overridden via the
+  // switches::kAuraHostWindowSize flag.
+  static bool use_fullscreen_host_window_;
+
+  // Used to schedule painting.
+  base::WeakPtrFactory<Desktop> schedule_paint_factory_;
+
   Window* active_window_;
 
   // Last location seen in a mouse event.