SF: Remove HWC plumbing for virtual display mirror

Replace the parameter, which is only relevant to SF-ARC, with a simpler
hook (virtual processDisplayAdded) that is closer to HWC-less overrides
for display creation.

Bug: 182939859
Test: Build
Change-Id: I9c8f84ec900d6538d9130c23a75ee79d1aefe13e
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 7e45dab..a790b4c 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -245,8 +245,7 @@
 }
 
 bool HWComposer::allocateVirtualDisplay(HalVirtualDisplayId displayId, ui::Size resolution,
-                                        ui::PixelFormat* format,
-                                        std::optional<PhysicalDisplayId> mirror) {
+                                        ui::PixelFormat* format) {
     if (!resolution.isValid()) {
         ALOGE("%s: Invalid resolution %dx%d", __func__, resolution.width, resolution.height);
         return false;
@@ -262,14 +261,9 @@
         return false;
     }
 
-    std::optional<hal::HWDisplayId> hwcMirrorId;
-    if (mirror) {
-        hwcMirrorId = fromPhysicalDisplayId(*mirror);
-    }
-
     hal::HWDisplayId hwcDisplayId;
     const auto error = static_cast<hal::Error>(
-            mComposer->createVirtualDisplay(width, height, format, hwcMirrorId, &hwcDisplayId));
+            mComposer->createVirtualDisplay(width, height, format, &hwcDisplayId));
     RETURN_IF_HWC_ERROR_FOR("createVirtualDisplay", error, displayId, false);
 
     auto display = std::make_unique<HWC2::impl::Display>(*mComposer.get(), mCapabilities,