Refactor Subzero initialization and add a browser callback handler.

src/IceClFlags.h

Index: src/IceClFlags.h
diff --git a/src/IceClFlags.h b/src/IceClFlags.h
index 1133f8ccc9eecc1ed63ee89589e6e6b2037ff17f..b581a24d5a34500f78920eeca53f9bbdcb88f8a0 100644
--- a/src/IceClFlags.h
+++ b/src/IceClFlags.h
@@ -14,10 +14,13 @@
 #ifndef SUBZERO_SRC_ICECLFLAGS_H
 #define SUBZERO_SRC_ICECLFLAGS_H
 
+#include "IceDefs.h"
 #include "IceTypes.h"
 
 namespace Ice {
 
+class ClFlagsExtra;
+
 class ClFlags {
   ClFlags(const ClFlags &) = delete;
   ClFlags &operator=(const ClFlags &) = delete;
@@ -33,7 +36,7 @@ public:
         RandomNopInsertion(false), RandomRegAlloc(false),
         SubzeroTimingEnabled(false), TimeEachFunction(false),
         UseSandboxing(false),
-        // Enum and integer fields
+        // Enum and integer fields.
         Opt(Opt_m1), OutFileType(FT_Iasm), RandomMaxNopsPerInstruction(0),
         RandomNopProbabilityAsPercentage(0), TArch(TargetArch_NUM),
         VMask(IceV_None),
@@ -43,6 +46,10 @@ public:
         // size_t and 64-bit fields.
         NumTranslationThreads(0), RandomSeed(0) {}
 
+  static void parseFlags(int argc, char *argv[]);
+  static void getParsedClFlags(ClFlags &OutFlags);
+  static void getParsedClFlagsExtra(ClFlagsExtra &OutFlagsExtra);
+
   // bool accessors.
 
   bool getAllowErrorRecovery() const { return AllowErrorRecovery; }