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/LayerBase.cpp b/services/surfaceflinger/LayerBase.cpp
index 2311e6d..a2513a2 100644
--- a/services/surfaceflinger/LayerBase.cpp
+++ b/services/surfaceflinger/LayerBase.cpp
@@ -41,8 +41,8 @@
 
 int32_t LayerBase::sSequence = 1;
 
-LayerBase::LayerBase(SurfaceFlinger* flinger, DisplayID display)
-    : dpy(display), contentDirty(false),
+LayerBase::LayerBase(SurfaceFlinger* flinger)
+    : contentDirty(false),
       sequence(uint32_t(android_atomic_inc(&sSequence))),
       mFlinger(flinger), mFiltering(false),
       mNeedsFiltering(false),
@@ -461,9 +461,9 @@
 
 int32_t LayerBaseClient::sIdentity = 1;
 
-LayerBaseClient::LayerBaseClient(SurfaceFlinger* flinger, DisplayID display,
+LayerBaseClient::LayerBaseClient(SurfaceFlinger* flinger,
         const sp<Client>& client)
-    : LayerBase(flinger, display),
+    : LayerBase(flinger),
       mHasSurface(false),
       mClientRef(client),
       mIdentity(uint32_t(android_atomic_inc(&sIdentity)))