Use the checksum in the dex header for anynomous vdex files.

We were breaking (non-fatal) assumptions that location
checksums are unique per dex file.

Test: test.py
Test: 692-vdex-inmem-loader
Change-Id: I3c2cf186bb244a7e89b9dd0ec9e68cadc4696d6e
diff --git a/runtime/oat_file_assistant.h b/runtime/oat_file_assistant.h
index 9f9c91f..8784875 100644
--- a/runtime/oat_file_assistant.h
+++ b/runtime/oat_file_assistant.h
@@ -249,14 +249,12 @@
                                        std::string* oat_filename,
                                        std::string* error_msg);
 
-  // Computes the location checksum, dex location and vdex filename by combining
-  // the checksums of the individual dex files. If the data directory of the process
+  // Computes the dex location and vdex filename. If the data directory of the process
   // is known, creates an absolute path in that directory and tries to infer path
   // of a corresponding vdex file. Otherwise only creates a basename dex_location
   // from the combined checksums. Returns true if all out-arguments have been set.
   static bool AnonymousDexVdexLocation(const std::vector<const DexFile::Header*>& dex_headers,
                                        InstructionSet isa,
-                                       /* out */ uint32_t* location_checksum,
                                        /* out */ std::string* dex_location,
                                        /* out */ std::string* vdex_filename);