Initial design for background compilation

runtime/vm/isolate.h

Index: runtime/vm/isolate.h
diff --git a/runtime/vm/isolate.h b/runtime/vm/isolate.h
index 265960c71bad4c62fa9c8c07d4ca5aaed7a2a0e2..7a251e0b6f061e50afab4e18219f13bd5b8e64a3 100644
--- a/runtime/vm/isolate.h
+++ b/runtime/vm/isolate.h
@@ -32,6 +32,7 @@ class CHA;
 class Class;
 class Code;
 class CodeIndexTable;
+class CompileOptimizedTask;
 class CompilerStats;
 class Debugger;
 class DeoptContext;
@@ -605,6 +606,13 @@ class Isolate : public BaseIsolate {
     deopt_context_ = value;
   }
 
+  CompileOptimizedTask* compile_optimized_task() const {
+    return compile_optimized_task_;
+  }
+  void set_compile_optimized_task(CompileOptimizedTask* value) {
+    compile_optimized_task_ = value;
+  }
+
   void UpdateLastAllocationProfileAccumulatorResetTimestamp() {
     last_allocationprofile_accumulator_reset_timestamp_ =
         OS::GetCurrentTimeMillis();
@@ -701,6 +709,11 @@ class Isolate : public BaseIsolate {
   }
   void set_collected_closures(const GrowableObjectArray& value);
 
+  RawGrowableObjectArray* background_compilation_queue() const {
+    return background_compilation_queue_;
+  }
+  void set_background_compilation_queue(const GrowableObjectArray& value);
+
   Metric* metrics_list_head() {
     return metrics_list_head_;
   }
@@ -875,6 +888,7 @@ class Isolate : public BaseIsolate {
   Dart_GcEpilogueCallback gc_epilogue_callback_;
   intptr_t defer_finalization_count_;
   DeoptContext* deopt_context_;
+  CompileOptimizedTask* compile_optimized_task_;
 
   CompilerStats* compiler_stats_;
 
@@ -905,6 +919,7 @@ class Isolate : public BaseIsolate {
 
   RawGrowableObjectArray* collected_closures_;
   RawGrowableObjectArray* deoptimized_code_array_;
+  RawGrowableObjectArray* background_compilation_queue_;
 
   // We use 6 list entries for each pending service extension calls.
   enum {