Let InputReader set mouse cursor's display.

InputReader was already responsible to bind device/event and display. It
makes sense to further extend it to control the display where mouse
cursor is shown.

Bug: 146385350
Test: Mouse cursor shows up at expected display.
Test: atest inputflinger_tests
Change-Id: Ie7a9546550b70c8834462b06de929472196fe713
diff --git a/services/inputflinger/reader/mapper/TouchInputMapper.cpp b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
index c80a2dc..b66caca 100644
--- a/services/inputflinger/reader/mapper/TouchInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
@@ -552,9 +552,10 @@
  * Determine which DisplayViewport to use.
  * 1. If display port is specified, return the matching viewport. If matching viewport not
  * found, then return.
- * 2. If a device has associated display, get the matching viewport by either unique id or by
+ * 2. Always use the suggested viewport from WindowManagerService for pointers.
+ * 3. If a device has associated display, get the matching viewport by either unique id or by
  * the display type (internal or external).
- * 3. Otherwise, use a non-display viewport.
+ * 4. Otherwise, use a non-display viewport.
  */
 std::optional<DisplayViewport> TouchInputMapper::findViewport() {
     if (mParameters.hasAssociatedDisplay) {
@@ -564,6 +565,17 @@
             return mDevice->getAssociatedViewport();
         }
 
+        if (mDeviceMode == DEVICE_MODE_POINTER) {
+            std::optional<DisplayViewport> viewport =
+                    mConfig.getDisplayViewportById(mConfig.defaultPointerDisplayId);
+            if (viewport) {
+                return viewport;
+            } else {
+                ALOGW("Can't find designated display viewport with ID %" PRId32 " for pointers.",
+                      mConfig.defaultPointerDisplayId);
+            }
+        }
+
         // Check if uniqueDisplayId is specified in idc file.
         if (!mParameters.uniqueDisplayId.empty()) {
             return mConfig.getDisplayViewportByUniqueId(mParameters.uniqueDisplayId);
@@ -749,6 +761,7 @@
         (mDeviceMode == DEVICE_MODE_DIRECT && mConfig.showTouches)) {
         if (mPointerController == nullptr || viewportChanged) {
             mPointerController = getPolicy()->obtainPointerController(getDeviceId());
+            mPointerController->setDisplayViewport(mViewport);
         }
     } else {
         mPointerController.clear();