Reapply "[vm] Don't enable the profiler by default. Enable the profiler at startup with --observe, …

runtime/vm/service_test.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/globals.h"
 
 #include "include/dart_tools_api.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/debugger.h"
 #include "vm/globals.h"
 #include "vm/message_handler.h"
 #include "vm/object_id_ring.h"
 #include "vm/os.h"
 #include "vm/port.h"
+#include "vm/profiler.h"
 #include "vm/safepoint.h"
 #include "vm/service.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 // This flag is used in the Service_Flags test below.
 DEFINE_FLAG(bool, service_testing_flag, false, "Comment");
 
 #ifndef PRODUCT
@@ skipping 692 matching lines @@
   service_msg = Eval(lib, "[0, port, '0', 'beta', [], []]");
   HandleIsolateMessage(isolate, service_msg);
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   EXPECT_STREQ("{\"jsonrpc\":\"2.0\", \"error\":beta,\"id\":\"0\"}",
                handler.msg());
 }
 
 // TODO(zra): Remove when tests are ready to enable.
 #if !defined(TARGET_ARCH_ARM64)
 
+static void EnableProfiler() {
+  if (!FLAG_profiler) {
+    FLAG_profiler = true;
+    Profiler::InitOnce();
+  }
+}
+
 TEST_CASE(Service_Profile) {
+  EnableProfiler();
   const char* kScript =
       "var port;\n"  // Set to our mock port by C++.
       "\n"
       "var x = 7;\n"
       "main() {\n"
       "  x = x * x;\n"
       "  x = x / 13;\n"
       "}";
 
   Isolate* isolate = thread->isolate();
@@ skipping 30 matching lines @@
   EXPECT_EQ(MessageHandler::kOK, handler.HandleNextMessage());
   // Expect error.
   EXPECT_SUBSTRING("\"error\"", handler.msg());
 }
 
 #endif  // !defined(TARGET_ARCH_ARM64)
 
 #endif  // !PRODUCT
 
 }  // namespace dart