Refine statistics around the JIT.

- Better namings.
- Now also time the code cache collection time.
- Random cleanups.

bug:23128949
bug:27445008
bug:27442890

Change-Id: I1dd52544bea678af868e7c47907f7a0fc9a146c3
diff --git a/compiler/jit/jit_compiler.cc b/compiler/jit/jit_compiler.cc
index 79a6d38..6ff1e2e 100644
--- a/compiler/jit/jit_compiler.cc
+++ b/compiler/jit/jit_compiler.cc
@@ -85,7 +85,7 @@
   exit(EXIT_FAILURE);
 }
 
-JitCompiler::JitCompiler() : total_time_(0) {
+JitCompiler::JitCompiler() {
   compiler_options_.reset(new CompilerOptions(
       CompilerOptions::kDefaultCompilerFilter,
       CompilerOptions::kDefaultHugeMethodThreshold,
@@ -195,7 +195,6 @@
 bool JitCompiler::CompileMethod(Thread* self, ArtMethod* method, bool osr) {
   DCHECK(!method->IsProxyMethod());
   TimingLogger logger("JIT compiler timing logger", true, VLOG_IS_ON(jit));
-  const uint64_t start_time = NanoTime();
   StackHandleScope<2> hs(self);
   self->AssertNoPendingException();
   Runtime* runtime = Runtime::Current();
@@ -236,7 +235,6 @@
     runtime->GetJitArenaPool()->TrimMaps();
   }
 
-  total_time_ += NanoTime() - start_time;
   runtime->GetJit()->AddTimingLogger(logger);
   return success;
 }