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

(cherry picked from commit 12f7423a2bb4bfab76700d84eb6d4338d211983a)

Bug: 18588862
Change-Id: Ic5a2781f704e931265ffb3621c2eab4b2e25f60f
diff --git a/runtime/runtime.cc b/runtime/runtime.cc
index e531091..9dddf2f 100644
--- a/runtime/runtime.cc
+++ b/runtime/runtime.cc
@@ -1221,33 +1221,15 @@
 
 void Runtime::VisitNonThreadRoots(RootCallback* callback, void* arg) {
   java_vm_->VisitRoots(callback, arg);
-  if (!sentinel_.IsNull()) {
-    sentinel_.VisitRoot(callback, arg, 0, kRootVMInternal);
-    DCHECK(!sentinel_.IsNull());
-  }
-  if (!pre_allocated_OutOfMemoryError_.IsNull()) {
-    pre_allocated_OutOfMemoryError_.VisitRoot(callback, arg, 0, kRootVMInternal);
-    DCHECK(!pre_allocated_OutOfMemoryError_.IsNull());
-  }
-  resolution_method_.VisitRoot(callback, arg, 0, kRootVMInternal);
-  DCHECK(!resolution_method_.IsNull());
-  if (!pre_allocated_NoClassDefFoundError_.IsNull()) {
-    pre_allocated_NoClassDefFoundError_.VisitRoot(callback, arg, 0, kRootVMInternal);
-    DCHECK(!pre_allocated_NoClassDefFoundError_.IsNull());
-  }
-  if (HasImtConflictMethod()) {
-    imt_conflict_method_.VisitRoot(callback, arg, 0, kRootVMInternal);
-  }
-  if (!imt_unimplemented_method_.IsNull()) {
-    imt_unimplemented_method_.VisitRoot(callback, arg, 0, kRootVMInternal);
-  }
-  if (HasDefaultImt()) {
-    default_imt_.VisitRoot(callback, arg, 0, kRootVMInternal);
-  }
+  sentinel_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
+  pre_allocated_OutOfMemoryError_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
+  resolution_method_.VisitRoot(callback, arg, RootInfo(kRootVMInternal));
+  pre_allocated_NoClassDefFoundError_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
+  imt_conflict_method_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
+  imt_unimplemented_method_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
+  default_imt_.VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
   for (int i = 0; i < Runtime::kLastCalleeSaveType; i++) {
-    if (!callee_save_methods_[i].IsNull()) {
-      callee_save_methods_[i].VisitRoot(callback, arg, 0, kRootVMInternal);
-    }
+    callee_save_methods_[i].VisitRootIfNonNull(callback, arg, RootInfo(kRootVMInternal));
   }
   verifier::MethodVerifier::VisitStaticRoots(callback, arg);
   {