Banish DisplayID from the SurfaceFlinger API.

Use only display tokens in the API to refer to new displays.

Don't require the caller to specify the display when creating
a surface (since in general a surface could be shown on
any display).

This is intended to be a minimum change just to update the API.
Note that SurfaceFlinger still uses DisplayID in a few places
internally that might cause some features not to work properly
when there are multiple displays (LayerScreenshot, for example).

Change-Id: I3d91eec2da406eefd97bcd53655d403ad865a7e6
diff --git a/services/surfaceflinger/tests/screencap/screencap.cpp b/services/surfaceflinger/tests/screencap/screencap.cpp
index 53566e0..f842fc3 100644
--- a/services/surfaceflinger/tests/screencap/screencap.cpp
+++ b/services/surfaceflinger/tests/screencap/screencap.cpp
@@ -42,7 +42,8 @@
     sp<IMemoryHeap> heap;
     uint32_t w, h;
     PixelFormat f;
-    status_t err = composer->captureScreen(0, &heap, &w, &h, &f, 0, 0);
+    sp<IBinder> display(composer->getBuiltInDisplay(ISurfaceComposer::eDisplayIdMain));
+    status_t err = composer->captureScreen(display, &heap, &w, &h, &f, 0, 0);
     if (err != NO_ERROR) {
         fprintf(stderr, "screen capture failed: %s\n", strerror(-err));
         exit(0);