Add context to gfx::Screen calls in support of simultaneous desktop+ash

chrome/browser/ui/host_desktop.h

Index: chrome/browser/ui/host_desktop.h
diff --git a/chrome/browser/ui/host_desktop.h b/chrome/browser/ui/host_desktop.h
index 2476ae635c4b69119bbf9eeb768c552f5f9f4fda..9cd6f44a1f49c9bca741dadc67515ee93dea15a9 100644
--- a/chrome/browser/ui/host_desktop.h
+++ b/chrome/browser/ui/host_desktop.h
@@ -5,14 +5,20 @@
 #ifndef CHROME_BROWSER_UI_HOST_DESKTOP_H_
 #define CHROME_BROWSER_UI_HOST_DESKTOP_H_
 
+#include "ui/gfx/native_widget_types.h"
+
+class Browser;
+
 namespace chrome {
 
 // A value that specifies what desktop environment hosts a particular piece of
 // UI.
 // Note that HOST_DESKTOP_TYPE_ASH is always used on ChromeOS.
 enum HostDesktopType {
+  HOST_DESKTOP_TYPE_FIRST = 0,
+
   // The UI is hosted on the system native desktop.
-  HOST_DESKTOP_TYPE_NATIVE = 0,
+  HOST_DESKTOP_TYPE_NATIVE = HOST_DESKTOP_TYPE_FIRST,
 
   // The UI is hosted in the synthetic Ash desktop.
 #if defined(OS_CHROMEOS)
@@ -24,13 +30,24 @@ enum HostDesktopType {
   HOST_DESKTOP_TYPE_COUNT
 };
 
-/*
-TODO(beng): implement utilities as needed, e.g.:
-HostDesktopType GetActiveDesktop();
+class ScopedForceDesktopType {
+ public:
+  explicit ScopedForceDesktopType(HostDesktopType type);
+  ~ScopedForceDesktopType();
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ScopedForceDesktopType);
+  HostDesktopType previous_type_;
+  bool previous_force_;
+};
+
 HostDesktopType GetHostDesktopTypeForNativeView(gfx::NativeView native_view);
 HostDesktopType GetHostDesktopTypeForNativeWindow(
     gfx::NativeWindow native_window);
-HostDesktopType GetHostDesktopTypeForBrowser(Browser* browser);
+HostDesktopType GetHostDesktopTypeForBrowser(const Browser* browser);
+
+/*
+TODO(beng): implement utilities as needed, e.g.:
+HostDesktopType GetActiveDesktop();
 */
 
 }  // namespace chrome