SF: Cleanup creating / destroying virtual display APIs

Follow-up CL for cleanup requested by SF owner in http://ag/27202517.

Misc:
- Fix type conversion warnings for print format.
- Return status destroying virtual display in SF and add appropriate
checks in UT.
- Use static constexpr / const for compile-time effciciency.

Bug: 339525838
Bug: 137375833
Bug: 194863377
Test: atest libsurfaceflinger_unittest
Test: atest SurfaceFlinger_test
Flag: EXEMPT refactor
Change-Id: I7859720989c9244b26f8764c3323a8495064c888
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 8474515..2363cd7 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -547,9 +547,10 @@
     status_t dump(int fd, const Vector<String16>& args) override { return priorityDump(fd, args); }
 
     // ISurfaceComposer implementation:
-    sp<IBinder> createDisplay(const String8& displayName, bool isSecure,
-                              const std::string& uniqueId, float requestedRefreshRate = 0.0f);
-    void destroyDisplay(const sp<IBinder>& displayToken);
+    sp<IBinder> createVirtualDisplay(const std::string& displayName, bool isSecure,
+                                     const std::string& uniqueId,
+                                     float requestedRefreshRate = 0.0f);
+    status_t destroyVirtualDisplay(const sp<IBinder>& displayToken);
     std::vector<PhysicalDisplayId> getPhysicalDisplayIds() const EXCLUDES(mStateLock) {
         Mutex::Autolock lock(mStateLock);
         return getPhysicalDisplayIdsLocked();
@@ -1568,10 +1569,10 @@
             const sp<IBinder>& layerHandle,
             sp<gui::IDisplayEventConnection>* outConnection) override;
     binder::Status createConnection(sp<gui::ISurfaceComposerClient>* outClient) override;
-    binder::Status createDisplay(const std::string& displayName, bool isSecure,
-                                 const std::string& uniqueId, float requestedRefreshRate,
-                                 sp<IBinder>* outDisplay) override;
-    binder::Status destroyDisplay(const sp<IBinder>& display) override;
+    binder::Status createVirtualDisplay(const std::string& displayName, bool isSecure,
+                                        const std::string& uniqueId, float requestedRefreshRate,
+                                        sp<IBinder>* outDisplay) override;
+    binder::Status destroyVirtualDisplay(const sp<IBinder>& displayToken) override;
     binder::Status getPhysicalDisplayIds(std::vector<int64_t>* outDisplayIds) override;
     binder::Status getPhysicalDisplayToken(int64_t displayId, sp<IBinder>* outDisplay) override;
     binder::Status setPowerMode(const sp<IBinder>& display, int mode) override;