[debugger] introduce abstract interface for break location.

src/debug/ppc/debug-ppc.cc

Index: src/debug/ppc/debug-ppc.cc
diff --git a/src/debug/ppc/debug-ppc.cc b/src/debug/ppc/debug-ppc.cc
index c5ddab8bc0b12200a9130ef0fee7fbde66599988..aab5399fee177d248fea1638ff66e7cc75b48f21 100644
--- a/src/debug/ppc/debug-ppc.cc
+++ b/src/debug/ppc/debug-ppc.cc
@@ -64,6 +64,10 @@ void DebugCodegen::PatchDebugBreakSlot(Isolate* isolate, Address pc,
   patcher.masm()->bctrl();
 }
 
+bool DebugCodegen::DebugBreakSlotIsPatched(Address pc) {
+  Instr current_instr = Assembler::instr_at(pc);
+  return !Assembler::IsNop(current_instr, Assembler::DEBUG_BREAK_NOP);
+}
 
 void DebugCodegen::GenerateDebugBreakStub(MacroAssembler* masm,
                                           DebugBreakCallHelperMode mode) {