Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/runtime/mirror/throwable.cc b/runtime/mirror/throwable.cc
index b564649..ca94644 100644
--- a/runtime/mirror/throwable.cc
+++ b/runtime/mirror/throwable.cc
@@ -45,7 +45,7 @@
   CHECK(cause != nullptr);
   CHECK(cause != this);
   Throwable* current_cause = GetFieldObject<Throwable>(OFFSET_OF_OBJECT_MEMBER(Throwable, cause_));
-  CHECK(current_cause == NULL || current_cause == this);
+  CHECK(current_cause == nullptr || current_cause == this);
   if (Runtime::Current()->IsActiveTransaction()) {
     SetFieldObject<true>(OFFSET_OF_OBJECT_MEMBER(Throwable, cause_), cause);
   } else {
@@ -80,7 +80,7 @@
   std::string result(PrettyTypeOf(this));
   result += ": ";
   String* msg = GetDetailMessage();
-  if (msg != NULL) {
+  if (msg != nullptr) {
     result += msg->ToModifiedUtf8();
   }
   result += "\n";
@@ -135,7 +135,7 @@
 
 void Throwable::SetClass(Class* java_lang_Throwable) {
   CHECK(java_lang_Throwable_.IsNull());
-  CHECK(java_lang_Throwable != NULL);
+  CHECK(java_lang_Throwable != nullptr);
   java_lang_Throwable_ = GcRoot<Class>(java_lang_Throwable);
 }