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

runtime/vm/profiler_test.cc

Index: runtime/vm/profiler_test.cc
diff --git a/runtime/vm/profiler_test.cc b/runtime/vm/profiler_test.cc
index c431944674fd809961d0a55100ba1c41ebf4f5c8..56c9e0310ca16e604d161b481915aaa50c8c17a1 100644
--- a/runtime/vm/profiler_test.cc
+++ b/runtime/vm/profiler_test.cc
@@ -189,7 +189,15 @@ class AllocationFilter : public SampleFilter {
   bool enable_vm_ticks_;
 };
 
+static void EnableProfiler() {
+  if (!FLAG_profiler) {
+    FLAG_profiler = true;
+    Profiler::InitOnce();
+  }
+}
+
 TEST_CASE(Profiler_TrivialRecordAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "class A {\n"
@@ -314,6 +322,8 @@ DART_NOINLINE static void NativeAllocationSampleHelper(char** result) {
 }
 
 ISOLATE_UNIT_TEST_CASE(Profiler_NativeAllocation) {
+  EnableProfiler();
+
   bool enable_malloc_hooks_saved = FLAG_profiler_native_memory;
   FLAG_profiler_native_memory = true;
 
@@ -516,6 +526,8 @@ ISOLATE_UNIT_TEST_CASE(Profiler_NativeAllocation) {
         // !defined(TARGET_ARCH_DBC) && !defined(HOST_OS_FUCHSIA)
 
 TEST_CASE(Profiler_ToggleRecordAllocation) {
+  EnableProfiler();
+
   DisableNativeProfileScope dnps;
   const char* kScript =
       "class A {\n"
@@ -645,6 +657,7 @@ TEST_CASE(Profiler_ToggleRecordAllocation) {
 }
 
 TEST_CASE(Profiler_CodeTicks) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "class A {\n"
@@ -747,6 +760,7 @@ TEST_CASE(Profiler_CodeTicks) {
 }
 
 TEST_CASE(Profiler_FunctionTicks) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "class A {\n"
@@ -849,6 +863,7 @@ TEST_CASE(Profiler_FunctionTicks) {
 }
 
 TEST_CASE(Profiler_IntrinsicAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript = "double foo(double a, double b) => a + b;";
   Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
@@ -920,6 +935,7 @@ TEST_CASE(Profiler_IntrinsicAllocation) {
 }
 
 TEST_CASE(Profiler_ArrayAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "List foo() => new List(4);\n"
@@ -1016,6 +1032,7 @@ TEST_CASE(Profiler_ArrayAllocation) {
 }
 
 TEST_CASE(Profiler_ContextAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "var msg1 = 'a';\n"
@@ -1085,6 +1102,7 @@ TEST_CASE(Profiler_ContextAllocation) {
 }
 
 TEST_CASE(Profiler_ClosureAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "var msg1 = 'a';\n"
@@ -1156,6 +1174,7 @@ TEST_CASE(Profiler_ClosureAllocation) {
 }
 
 TEST_CASE(Profiler_TypedArrayAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript =
       "import 'dart:typed_data';\n"
@@ -1240,6 +1259,7 @@ TEST_CASE(Profiler_TypedArrayAllocation) {
 }
 
 TEST_CASE(Profiler_StringAllocation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   const char* kScript = "String foo(String a, String b) => a + b;";
   Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
@@ -1325,6 +1345,7 @@ TEST_CASE(Profiler_StringAllocation) {
 }
 
 TEST_CASE(Profiler_StringInterpolation) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   const char* kScript = "String foo(String a, String b) => '$a | $b';";
@@ -1413,6 +1434,7 @@ TEST_CASE(Profiler_StringInterpolation) {
 }
 
 TEST_CASE(Profiler_FunctionInline) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
 
@@ -1702,6 +1724,7 @@ TEST_CASE(Profiler_InliningIntervalBoundry) {
   // This test checks the profiler service takes this into account; see
   // ProfileBuilder::ProcessFrame.
 
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   const char* kScript =
@@ -1833,6 +1856,7 @@ TEST_CASE(Profiler_InliningIntervalBoundry) {
 }
 
 TEST_CASE(Profiler_ChainedSamples) {
+  EnableProfiler();
   MaxProfileDepthScope mpds(32);
   DisableNativeProfileScope dnps;
 
@@ -1945,6 +1969,7 @@ TEST_CASE(Profiler_ChainedSamples) {
 }
 
 TEST_CASE(Profiler_BasicSourcePosition) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   const char* kScript =
@@ -2019,6 +2044,7 @@ TEST_CASE(Profiler_BasicSourcePosition) {
 }
 
 TEST_CASE(Profiler_BasicSourcePositionOptimized) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   // We use the AlwaysInline and NeverInline annotations in this test.
@@ -2112,6 +2138,7 @@ TEST_CASE(Profiler_BasicSourcePositionOptimized) {
 }
 
 TEST_CASE(Profiler_SourcePosition) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   const char* kScript =
@@ -2216,6 +2243,7 @@ TEST_CASE(Profiler_SourcePosition) {
 }
 
 TEST_CASE(Profiler_SourcePositionOptimized) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   // We use the AlwaysInline and NeverInline annotations in this test.
@@ -2340,6 +2368,7 @@ TEST_CASE(Profiler_SourcePositionOptimized) {
 }
 
 TEST_CASE(Profiler_BinaryOperatorSourcePosition) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   const char* kScript =
@@ -2453,6 +2482,7 @@ TEST_CASE(Profiler_BinaryOperatorSourcePosition) {
 }
 
 TEST_CASE(Profiler_BinaryOperatorSourcePositionOptimized) {
+  EnableProfiler();
   DisableNativeProfileScope dnps;
   DisableBackgroundCompilationScope dbcs;
   // We use the AlwaysInline and NeverInline annotations in this test.
@@ -2625,6 +2655,7 @@ static uword FindPCForTokenPosition(const Code& code, TokenPosition tp) {
 }
 
 TEST_CASE(Profiler_GetSourceReport) {
+  EnableProfiler();
   const char* kScript =
       "doWork(i) => i * i;\n"
       "main() {\n"