Introduce Perf Monitor

Summary: public

Kill `RCTPerfStats` and introduce the new `RCTPerfMonitor`, including memory
usage, JSC heap size, number of RN views in screen, FPS (both on UI and JS threads)
and more to come.

It removes all the previous traces that were previous spread across the bridge
and the dev menu and moves everything to be more contained, so the whole thing
can be safely striped in production.

Reviewed By: nicklockwood

Differential Revision: D2575158

fb-gh-sync-id: 6a6d0c4422adbddeeefddd32ec3409a7095ff2a9

React/Base/RCTBatchedBridge.m

@@ -20,7 +20,6 @@
 #import "RCTModuleMap.h"
 #import "RCTBridgeMethod.h"
 #import "RCTPerformanceLogger.h"
-#import "RCTPerfStats.h"
 #import "RCTProfile.h"
 #import "RCTRedBox.h"
 #import "RCTSourceCode.h"
@@ -68,7 +67,6 @@ @implementation RCTBatchedBridge
   NSMutableArray *_pendingCalls;
   NSMutableArray *_moduleDataByID;
   RCTModuleMap *_modulesByName;
-  CADisplayLink *_mainDisplayLink;
   CADisplayLink *_jsDisplayLink;
   NSMutableSet *_frameUpdateObservers;
 }
@@ -94,11 +92,6 @@ - (instancetype)initWithParentBridge:(RCTBridge *)bridge
     _frameUpdateObservers = [NSMutableSet new];
     _jsDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(_jsThreadUpdate:)];
 
-    if (RCT_DEV) {
-      _mainDisplayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(_mainThreadUpdate:)];
-      [_mainDisplayLink addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
-    }
-
     [RCTBridge setCurrentBridge:self];
 
     [[NSNotificationCenter defaultCenter] postNotificationName:RCTJavaScriptWillStartLoadingNotification
@@ -508,9 +501,6 @@ - (void)invalidate
     [RCTBridge setCurrentBridge:nil];
   }
 
-  [_mainDisplayLink invalidate];
-  _mainDisplayLink = nil;
-
   // Invalidate modules
   dispatch_group_t group = dispatch_group_create();
   for (RCTModuleData *moduleData in _moduleDataByID) {
@@ -868,21 +858,6 @@ - (void)_jsThreadUpdate:(CADisplayLink *)displayLink
   RCTProfileImmediateEvent(0, @"JS Thread Tick", 'g');
 
   RCTProfileEndEvent(0, @"objc_call", nil);
-
-  RCT_IF_DEV(
-    dispatch_async(dispatch_get_main_queue(), ^{
-      [self.perfStats.jsGraph onTick:displayLink.timestamp];
-    });
-  )
-}
-
-- (void)_mainThreadUpdate:(CADisplayLink *)displayLink
-{
-  RCTAssertMainThread();
-
-  RCTProfileImmediateEvent(0, @"VSYNC", 'g');
-
-  _modulesByName == nil ?: [self.perfStats.uiGraph onTick:displayLink.timestamp];
 }
 
 - (void)startProfiling