Add UMA stats for pen palette

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

Index: ash/common/system/chromeos/palette/palette_ids.cc
diff --git a/ash/common/system/chromeos/palette/palette_ids.cc b/ash/common/system/chromeos/palette/palette_ids.cc
index 5d5f48510d7e1d758636f06c617f00010fd182ff..010a8c676ead7e12eec71f9bb7eac671d35962bf 100644
--- a/ash/common/system/chromeos/palette/palette_ids.cc
+++ b/ash/common/system/chromeos/palette/palette_ids.cc
@@ -39,4 +39,24 @@ std::string PaletteGroupToString(PaletteGroup group) {
   return std::string();
 }
 
+PaletteTrayOptions PaletteToolIdToPaletteTrayOptions(PaletteToolId tool_id) {
+  switch (tool_id) {
+    case PaletteToolId::NONE:
+      return PALETTE_OPTIONS_COUNT;
+    case PaletteToolId::CREATE_NOTE:
+      return PALETTE_NEW_NOTE;
+    case PaletteToolId::CAPTURE_REGION:
+      return PALETTE_CAPTURE_REGION;
+    case PaletteToolId::CAPTURE_SCREEN:
+      return PALETTE_CAPTURE_SCREEN;
+    case PaletteToolId::LASER_POINTER:
+      return PALETTE_LASER_POINTER;
+    case PaletteToolId::MAGNIFY:
+      return PALETTE_MAGNIFY;
+  }
+
+  NOTREACHED();
+  return PALETTE_OPTIONS_COUNT;
+}
+
 }  // namespace ash