Clarify/fix fullscreen semantics, and add GetScreenSize

ppapi/c/dev/ppb_fullscreen_dev.h

Index: ppapi/c/dev/ppb_fullscreen_dev.h
diff --git a/ppapi/c/dev/ppb_fullscreen_dev.h b/ppapi/c/dev/ppb_fullscreen_dev.h
index ebf2adef024078a1262ac4193aa58d094fdd8ccf..ed91ed1e196fdb6b1636780222b95f3031344f5e 100644
--- a/ppapi/c/dev/ppb_fullscreen_dev.h
+++ b/ppapi/c/dev/ppb_fullscreen_dev.h
@@ -7,9 +7,10 @@
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
+#include "ppapi/c/pp_size.h"
 #include "ppapi/c/pp_stdint.h"
 
-#define PPB_FULLSCREEN_DEV_INTERFACE "PPB_Fullscreen(Dev);0.3"
+#define PPB_FULLSCREEN_DEV_INTERFACE "PPB_Fullscreen(Dev);0.4"
 
 // Use this interface to change a plugin instance to fullscreen mode.
 struct PPB_Fullscreen_Dev {
@@ -18,11 +19,19 @@ struct PPB_Fullscreen_Dev {
 
   // Switches the plugin instance to/from fullscreen mode. Returns PP_TRUE on
   // success, PP_FALSE on failure.
-  // When in fullscreen mode, the plugin will be transparently scaled to the
-  // size of the screen. It will not receive a ViewChanged event, and doesn't
-  // need to rebind the graphics context. The pending flushes will execute
-  // normally, to the new fullscreen window.
+  // This unbinds the current Graphics2D or Surface3D. Pending flushes and
+  // swapbuffers will execute as if the resource was off-screen.  The transition
+  // is asynchronous. During the transition, IsFullscreen will return PP_False,
+  // and no Graphics2D or Surface3D can be bound. The transition ends at the
+  // next DidChangeView.
+  // Note: when switching to and from fullscreen, Context3D and Surface3D
+  // resources need to be re-created. This is a current limitation that will be
+  // lifted in a later revision.
   PP_Bool (*SetFullscreen)(PP_Instance instance, PP_Bool fullscreen);
+
+  // Gets the size of the screen. When going fullscreen, the instance will be
+  // resized to that size.
+  PP_Bool (*GetScreenSize)(PP_Instance instance, struct PP_Size* size);
 };
 
 #endif  /* PPAPI_C_DEV_PPB_FULLSCREEN_DEV_H_ */