Use the interpreter as a heartbeat for the JIT.

When doing a partial code cache collection, update all entrypoints to
interpreter, so that the next full collection will remove code
that wasn't executed during that window.

bug:27398183
bug:23128949
bug:26846185

Change-Id: I4423f5c4810dac183dc8973078bf218818745e80
diff --git a/runtime/jit/jit.h b/runtime/jit/jit.h
index 109ca3d..3f54192 100644
--- a/runtime/jit/jit.h
+++ b/runtime/jit/jit.h
@@ -84,8 +84,12 @@
   // into the specified class linker to the jit debug interface,
   void DumpTypeInfoForLoadedTypes(ClassLinker* linker);
 
+  // Return whether we should try to JIT compiled code as soon as an ArtMethod is invoked.
   bool JitAtFirstUse();
 
+  // Return whether we can invoke JIT code for `method`.
+  bool CanInvokeCompiledCode(ArtMethod* method);
+
   // If an OSR compiled version is available for `method`,
   // and `dex_pc + dex_pc_offset` is an entry point of that compiled
   // version, this method will jump to the compiled code, let it run,