Change InputReader::getInputDevices to return vector of InputDeviceInfo.

Bug: 160010896
Test: atest inputflinger, atest libinput_tests
Change-Id: I27bc4b8b1b632d18658916e167915741117e58d7
diff --git a/services/inputflinger/include/InputReaderBase.h b/services/inputflinger/include/InputReaderBase.h
index 573524e..ffd8bf2 100644
--- a/services/inputflinger/include/InputReaderBase.h
+++ b/services/inputflinger/include/InputReaderBase.h
@@ -78,7 +78,7 @@
      *
      * This method may be called on any thread (usually by the input manager).
      */
-    virtual void getInputDevices(std::vector<InputDeviceInfo>& outInputDevices) = 0;
+    virtual std::vector<InputDeviceInfo> getInputDevices() const = 0;
 
     /* Query current input state. */
     virtual int32_t getScanCodeState(int32_t deviceId, uint32_t sourceMask,