ART: Print C1vis header only if visualizer enabled

Setting kStringFilter currently suppresses graph dumps of non-matching
methods but their headers are still printed. This fixes the issue.

Change-Id: Ib33fb20fcca2bf409534a824e7f76f1feb85724d
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 49c0d38..4c28378 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -337,13 +337,11 @@
 
 HGraphVisualizer::HGraphVisualizer(std::ostream* output,
                                    HGraph* graph,
-                                   const CodeGenerator& codegen,
-                                   const char* method_name)
-  : output_(output), graph_(graph), codegen_(codegen) {
-  if (output == nullptr) {
-    return;
-  }
+                                   const CodeGenerator& codegen)
+  : output_(output), graph_(graph), codegen_(codegen) {}
 
+void HGraphVisualizer::PrintHeader(const char* method_name) const {
+  DCHECK(output_ != nullptr);
   HGraphVisualizerPrinter printer(graph_, *output_, "", true, codegen_);
   printer.StartTag("compilation");
   printer.PrintProperty("name", method_name);
diff --git a/compiler/optimizing/graph_visualizer.h b/compiler/optimizing/graph_visualizer.h
index bc553ae..513bceb 100644
--- a/compiler/optimizing/graph_visualizer.h
+++ b/compiler/optimizing/graph_visualizer.h
@@ -35,9 +35,9 @@
  public:
   HGraphVisualizer(std::ostream* output,
                    HGraph* graph,
-                   const CodeGenerator& codegen,
-                   const char* method_name);
+                   const CodeGenerator& codegen);
 
+  void PrintHeader(const char* method_name) const;
   void DumpGraph(const char* pass_name, bool is_after_pass = true) const;
 
  private:
diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index e474c49..90a530a 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -96,10 +96,13 @@
         timing_logger_enabled_(compiler_driver->GetDumpPasses()),
         timing_logger_(method_name, true, true),
         visualizer_enabled_(!compiler_driver->GetDumpCfgFileName().empty()),
-        visualizer_(visualizer_output, graph, codegen, method_name_) {
+        visualizer_(visualizer_output, graph, codegen) {
     if (strstr(method_name, kStringFilter) == nullptr) {
       timing_logger_enabled_ = visualizer_enabled_ = false;
     }
+    if (visualizer_enabled_) {
+      visualizer_.PrintHeader(method_name_);
+    }
   }
 
   ~PassInfoPrinter() {