Eradicate DisplayID.

DisplayDevices are now keyed of the wp<IBinder> the client uses.
DisplayID has now become DisplayType which is just used to identify
physical displays (as opposed to virtual displays such as wifi displays).

Change-Id: I0c5968f2c902dcd699a7e0afacf833ff070c12ea
diff --git a/services/surfaceflinger/LayerScreenshot.h b/services/surfaceflinger/LayerScreenshot.h
index c06c23c..7807ffc 100644
--- a/services/surfaceflinger/LayerScreenshot.h
+++ b/services/surfaceflinger/LayerScreenshot.h
@@ -35,8 +35,7 @@
     GLfloat mTexCoords[8];
     sp<SurfaceFlinger> mFlinger;
 public:    
-            LayerScreenshot(SurfaceFlinger* flinger, DisplayID display,
-                        const sp<Client>& client);
+            LayerScreenshot(SurfaceFlinger* flinger, const sp<Client>& client);
         virtual ~LayerScreenshot();
 
         status_t capture();
@@ -51,7 +50,7 @@
     virtual const char* getTypeId() const { return "LayerScreenshot"; }
 
 private:
-    status_t captureLocked();
+    status_t captureLocked(int32_t layerStack);
     void initTexture(GLfloat u, GLfloat v);
 };