Print more info in MarkSweep::VerifyRoot

Refactored old root callback to use a new class called RootInfo.
RootInfo contains all the relevant info related to the root
associated with the callback. The MarkSweep::VerifyRoot function
now uses this info to print the StackVisitor's described location
if the GC root is of the type kRootJavaFrame.

Some other cleanup.

Example output:
E/art     (12167): Tried to mark 0x123 not contained by any spaces
E/art     (12167): Attempting see if it's a bad root
E/art     (12167): Found invalid root: 0x123 with type RootJavaFrame
E/art     (12167): Location=Visiting method
'void java.lang.Runtime.gc()' at dex PC 0xffffffff (native PC 0x0)
vreg=0

Bug: 18588862
Change-Id: Ic5a2781f704e931265ffb3621c2eab4b2e25f60f
diff --git a/runtime/intern_table.cc b/runtime/intern_table.cc
index 29a2459..144b2c5 100644
--- a/runtime/intern_table.cc
+++ b/runtime/intern_table.cc
@@ -60,7 +60,7 @@
   } else if ((flags & kVisitRootFlagNewRoots) != 0) {
     for (auto& root : new_strong_intern_roots_) {
       mirror::String* old_ref = root.Read<kWithoutReadBarrier>();
-      root.VisitRoot(callback, arg, 0, kRootInternedString);
+      root.VisitRoot(callback, arg, RootInfo(kRootInternedString));
       mirror::String* new_ref = root.Read<kWithoutReadBarrier>();
       if (new_ref != old_ref) {
         // The GC moved a root in the log. Need to search the strong interns and update the
@@ -329,10 +329,10 @@
 
 void InternTable::Table::VisitRoots(RootCallback* callback, void* arg) {
   for (auto& intern : pre_zygote_table_) {
-    intern.VisitRoot(callback, arg, 0, kRootInternedString);
+    intern.VisitRoot(callback, arg, RootInfo(kRootInternedString));
   }
   for (auto& intern : post_zygote_table_) {
-    intern.VisitRoot(callback, arg, 0, kRootInternedString);
+    intern.VisitRoot(callback, arg, RootInfo(kRootInternedString));
   }
 }