inputflinger: Initial support for rotary encoders.

This change introduces support for rotary encoder input devices.

We also define a new input source (namely, AINPUT_SOURCE_ROTARY_ENCODER)
and a new axis of input (namely, AXIS_SCROLL), since the rotary encoder
motion doesn't necessarily tie to a horizontal or vertical scroll
motion.

A ROTARY_ENCODER input device class is also introduced, corresponding to
the new input source.

A new input source can be defined as producing rotary encoder motion
events, if its corresponding .idc file contains the following
declaration:

    device.type = rotaryEncoder

Bug: 18707397

Change-Id: I8ccd540908311d1ff44fdfeba81b691895413641
Signed-off-by: Prashant Malani <pmalani@google.com>
diff --git a/services/inputflinger/InputReader.h b/services/inputflinger/InputReader.h
index 7cb4680..58db3dc 100644
--- a/services/inputflinger/InputReader.h
+++ b/services/inputflinger/InputReader.h
@@ -1232,6 +1232,26 @@
 };
 
 
+class RotaryEncoderInputMapper : public InputMapper {
+public:
+    RotaryEncoderInputMapper(InputDevice* device);
+    virtual ~RotaryEncoderInputMapper();
+
+    virtual uint32_t getSources();
+    virtual void populateDeviceInfo(InputDeviceInfo* deviceInfo);
+    virtual void dump(String8& dump);
+    virtual void configure(nsecs_t when, const InputReaderConfiguration* config, uint32_t changes);
+    virtual void reset(nsecs_t when);
+    virtual void process(const RawEvent* rawEvent);
+
+private:
+    CursorScrollAccumulator mRotaryEncoderScrollAccumulator;
+
+    int32_t mSource;
+
+    void sync(nsecs_t when);
+};
+
 class TouchInputMapper : public InputMapper {
 public:
     TouchInputMapper(InputDevice* device);