Add support for HAL_PIXEL_FORMAT_YCbCr_420_888

- Add fields to CpuConsumer::LockedBuffer for new information
- New lock methods for GraphicBuffer and GraphicBufferMapper for
  the format

Bug: 8734880
Change-Id: If31f82c62d64b6942cf4cc6e5715585c03273f12
diff --git a/include/ui/GraphicBufferMapper.h b/include/ui/GraphicBufferMapper.h
index 697a02a..99d8723 100644
--- a/include/ui/GraphicBufferMapper.h
+++ b/include/ui/GraphicBufferMapper.h
@@ -45,6 +45,9 @@
     status_t lock(buffer_handle_t handle,
             int usage, const Rect& bounds, void** vaddr);
 
+    status_t lockYCbCr(buffer_handle_t handle,
+            int usage, const Rect& bounds, android_ycbcr *ycbcr);
+
     status_t unlock(buffer_handle_t handle);
     
     // dumps information about the mapping of this handle