Add option to start sampling profiler on app launch

Reviewed By: mhorowitz

Differential Revision: D4415989

fbshipit-source-id: 30704c2b618656cb7cc0ccdf87dec315b30b62f3

React/Modules/RCTDevMenu.mm

@@ -212,6 +212,9 @@ RCT_EXPORT_MODULE()
       self->_executorOverride = [self->_defaults objectForKey:@"executor-override"];
     });
 
+    // Same values are read during the bridge starup path
+    _startSamplingProfilerOnLaunch = [_settings[@"startSamplingProfilerOnLaunch"] boolValue];
+
     // Delay setup until after Bridge init
     dispatch_async(dispatch_get_main_queue(), ^{
       [weakSelf updateSettings:self->_settings];
@@ -537,6 +540,8 @@ RCT_EXPORT_MODULE()
   }
 
   // Add toggles for JSC's sampling profiler, if the profiler is enabled
+  // Note: bridge.jsContext is not implemented in the old bridge, so this code is
+  // duplicated in RCTJSCExecutor
   if (JSC_JSSamplingProfilerEnabled(self->_bridge.jsContext.JSGlobalContextRef)) {
     JSContext *context = self->_bridge.jsContext;
     // Allow to toggle the sampling profiler through RN's dev menu
@@ -625,6 +630,12 @@ RCT_EXPORT_METHOD(debugRemotely:(BOOL)enableDebug)
   [self updateSetting:@"shakeToShow" value:@(_shakeToShow)];
 }
 
+- (void)setStartSamplingProfilerOnLaunch:(BOOL)startSamplingProfilerOnLaunch
+{
+  _startSamplingProfilerOnLaunch = startSamplingProfilerOnLaunch;
+  [self updateSetting:@"startSamplingProfilerOnLaunch" value:@(_startSamplingProfilerOnLaunch)];
+}
+
 RCT_EXPORT_METHOD(setProfilingEnabled:(BOOL)enabled)
 {
   _profilingEnabled = enabled;