Avoid std::string allocations for finding an array class.

Introduce ClassLinker::FindArrayClass which performs an array class lookup
given the element/component class. This has a 16 element cache of recently
looked up arrays.
Pass the current thread to ClassLinker Find .. Class routines to avoid calls
to Thread::Current().
Avoid some uses of FindClass in the debugger where WellKnownClasses is a
faster and more compacting GC friendly alternative.

Change-Id: I60e231820b349543a7edb3ceb9cf1ce92db3c843
diff --git a/runtime/verifier/method_verifier.cc b/runtime/verifier/method_verifier.cc
index ab943a6..ffa8b9e 100644
--- a/runtime/verifier/method_verifier.cc
+++ b/runtime/verifier/method_verifier.cc
@@ -3129,14 +3129,15 @@
     this_class = actual_arg_type.GetClass();
   } else {
     const std::string& descriptor(actual_arg_type.GetDescriptor());
+    Thread* self = Thread::Current();
     ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
-    this_class = class_linker->FindClass(descriptor.c_str(), *class_loader_);
+    this_class = class_linker->FindClass(self, descriptor.c_str(), *class_loader_);
     if (this_class == NULL) {
       Thread* self = Thread::Current();
       self->ClearException();
       // Look for a system class
       SirtRef<mirror::ClassLoader> null_class_loader(self, nullptr);
-      this_class = class_linker->FindClass(descriptor.c_str(), null_class_loader);
+      this_class = class_linker->FindClass(self, descriptor.c_str(), null_class_loader);
     }
   }
   if (this_class == NULL) {
@@ -3638,7 +3639,7 @@
 // Returns the access field of a quick field access (iget/iput-quick) or NULL
 // if it cannot be found.
 mirror::ArtField* MethodVerifier::GetQuickFieldAccess(const Instruction* inst,
-                                                   RegisterLine* reg_line) {
+                                                      RegisterLine* reg_line) {
   DCHECK(inst->Opcode() == Instruction::IGET_QUICK ||
          inst->Opcode() == Instruction::IGET_WIDE_QUICK ||
          inst->Opcode() == Instruction::IGET_OBJECT_QUICK ||
@@ -3654,12 +3655,12 @@
     const std::string& descriptor(object_type.GetDescriptor());
     ClassLinker* class_linker = Runtime::Current()->GetClassLinker();
     Thread* self = Thread::Current();
-    object_class = class_linker->FindClass(descriptor.c_str(), *class_loader_);
+    object_class = class_linker->FindClass(self, descriptor.c_str(), *class_loader_);
     if (object_class == NULL) {
       self->ClearException();
       // Look for a system class
       SirtRef<mirror::ClassLoader> null_class_loader(self, nullptr);
-      object_class = class_linker->FindClass(descriptor.c_str(), null_class_loader);
+      object_class = class_linker->FindClass(self, descriptor.c_str(), null_class_loader);
     }
   }
   if (object_class == NULL) {