Cleanup app snapshots on isolate/vm exit.

runtime/bin/snapshot_utils.h

Index: runtime/bin/snapshot_utils.h
diff --git a/runtime/bin/snapshot_utils.h b/runtime/bin/snapshot_utils.h
index fa667776f00b33332488932c5c65bbea9db2c0d9..758b38634db95428d5c2914e2162d690b7135543 100644
--- a/runtime/bin/snapshot_utils.h
+++ b/runtime/bin/snapshot_utils.h
@@ -10,6 +10,22 @@
 namespace dart {
 namespace bin {
 
+class AppSnapshot {
+ public:
+  virtual ~AppSnapshot() {}
+
+  virtual void SetBuffers(const uint8_t** vm_data_buffer,
+                          const uint8_t** vm_instructions_buffer,
+                          const uint8_t** isolate_data_buffer,
+                          const uint8_t** isolate_instructions_buffer) = 0;
+
+ protected:
+  AppSnapshot() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AppSnapshot);
+};
+
 class Snapshot {
  public:
   static void GenerateScript(const char* snapshot_filename);
@@ -17,11 +33,7 @@ class Snapshot {
   static void GenerateAppAOTAsBlobs(const char* snapshot_filename);
   static void GenerateAppAOTAsAssembly(const char* snapshot_filename);
 
-  static bool ReadAppSnapshot(const char* script_name,
-                              const uint8_t** vm_data_buffer,
-                              const uint8_t** vm_instructions_buffer,
-                              const uint8_t** isolate_data_buffer,
-                              const uint8_t** isolate_instructions_buffer);
+  static AppSnapshot* TryReadAppSnapshot(const char* script_name);
 
  private:
   DISALLOW_ALLOCATION();