Add UMA stats for pen palette

ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc

Index: ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc
diff --git a/ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc b/ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc
index 45b4c416aa20965a48ae37200b5e470419116b37..9db9647a4f3e21e9d103145124b27dfe86e1b3de 100644
--- a/ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc
+++ b/ash/common/system/chromeos/palette/palette_tool_manager_unittest.cc
@@ -58,6 +58,8 @@ class PaletteToolManagerTest : public ::testing::Test,
     NOTREACHED();
     return nullptr;
   }
+  void RecordPaletteOptionsUsage(PaletteTrayOptions option) override {}
+  void RecordPaletteModeCancellation(PaletteModeCancelType type) override {}
 
   // PaletteTool::Delegate:
   void EnableTool(PaletteToolId tool_id) override {}