Add API to get KeyCode produced by physical key location.

The physical key location is provided as a location KeyCode pointing to a location on a US keyboard layout.

Bug: 179812917
Test: atest KeyboardLayoutChangeTest
Test: atest android.hardware.input.cts.tests -m
Test: atest inputflinger_tests -m
Change-Id: Ib5ed41890cbbe393ee9ada1a04cbaaf82c9bb1fc
diff --git a/services/inputflinger/reader/mapper/TouchInputMapper.cpp b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
index 0a5de27..4772beb 100644
--- a/services/inputflinger/reader/mapper/TouchInputMapper.cpp
+++ b/services/inputflinger/reader/mapper/TouchInputMapper.cpp
@@ -178,7 +178,7 @@
 
 TouchInputMapper::~TouchInputMapper() {}
 
-uint32_t TouchInputMapper::getSources() {
+uint32_t TouchInputMapper::getSources() const {
     return mSource;
 }