ash: Rename AppLaunchId to ShelfID.

ash/public/cpp/shelf_types.h

Index: ash/public/cpp/shelf_types.h
diff --git a/ash/public/cpp/shelf_types.h b/ash/public/cpp/shelf_types.h
index c32f9db6b1d45461462db210013781645d312db6..a198dfa94601c8962f0120268bbd662ac8a9efea 100644
--- a/ash/public/cpp/shelf_types.h
+++ b/ash/public/cpp/shelf_types.h
@@ -6,8 +6,8 @@
 #define ASH_PUBLIC_CPP_SHELF_TYPES_H_
 
 #include <cstdint>
+#include <string>
 
-#include "ash/public/cpp/app_launch_id.h"
 #include "ash/public/cpp/ash_public_export.h"
 
 namespace ash {
@@ -90,9 +90,6 @@ enum ShelfAction {
   SHELF_ACTION_APP_LIST_SHOWN,
 };
 
-// TODO(msw): Rename AppLaunchId to ShelfID.
-using ShelfID = AppLaunchId;
-
 // The type of a shelf item.
 enum ShelfItemType {
   // Represents a running app panel.
@@ -135,6 +132,33 @@ enum ShelfItemStatus {
   STATUS_ATTENTION,
 };
 
+// A unique shelf item id composed of an |app_id| and a |launch_id|.
+// |app_id| is the non-empty application id associated with a set of windows.
+// |launch_id| is passed on app launch, to support multiple shelf items per app.
+// As an example, a remote desktop client may want each remote application to
+// have its own icon.
+struct ASH_PUBLIC_EXPORT ShelfID {
+  ShelfID(const std::string& app_id = std::string(),
+          const std::string& launch_id = std::string());
+  ~ShelfID();
+
+  ShelfID(const ShelfID& other);
+  ShelfID(ShelfID&& other);
+  ShelfID& operator=(const ShelfID& other);
+  bool operator==(const ShelfID& other) const;
+  bool operator!=(const ShelfID& other) const;
+  bool operator<(const ShelfID& other) const;
+
+  // Returns true if both the application id and launch id are empty.
+  // This is often used to determine if the id is invalid.
+  bool IsNull() const;
+
+  // The application id associated with a set of windows.
+  std::string app_id;
+  // An id passed on app launch, to support multiple shelf items per app.
+  std::string launch_id;
+};
+
 }  // namespace ash
 
 #endif  // ASH_PUBLIC_CPP_SHELF_TYPES_H_