Disable JsTranslateManagerTest.PerformancePlaceholder due to flakiness.

components/translate/ios/browser/js_translate_manager_unittest.mm

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "components/translate/ios/browser/js_translate_manager.h"
 
 #import "base/mac/scoped_nsobject.h"
 #include "base/strings/sys_string_conversions.h"
 #include "grit/components_resources.h"
 #import "ios/web/public/test/fakes/crw_test_js_injection_receiver.h"
@@ skipping 29 matching lines @@
   bool IsDefined(NSString* name) {
     NSString* script =
         [NSString stringWithFormat:@"typeof %@ != 'undefined'", name];
     return [web::ExecuteJavaScript(receiver_, script) boolValue];
   }
 
   base::scoped_nsobject<CRWTestJSInjectionReceiver> receiver_;
   base::scoped_nsobject<JsTranslateManager> manager_;
 };
 
-TEST_F(JsTranslateManagerTest, PerformancePlaceholder) {
+// TODO(crbug.com/658619#c47): Test reported as flaky.
+TEST_F(JsTranslateManagerTest, DISABLED_PerformancePlaceholder) {
   [manager_ inject];
   EXPECT_TRUE(IsDefined(@"performance"));
   EXPECT_TRUE(IsDefined(@"performance.now"));
 
   // Check that performance.now returns correct values.
   NSTimeInterval intervalInSeconds = 0.3;
   double startTime = [manager_ performanceNow];
   [NSThread sleepForTimeInterval:intervalInSeconds];
   double endTime = [manager_ performanceNow];
   double timeElapsed = endTime - startTime;
   // The tolerance is high to avoid flake.
   EXPECT_NEAR(timeElapsed, intervalInSeconds * 1000, 100);
 }
 
 TEST_F(JsTranslateManagerTest, Inject) {
   [manager_ inject];
   EXPECT_TRUE([manager_ hasBeenInjected]);
   EXPECT_EQ(nil, [manager_ script]);
   EXPECT_NSEQ(@NO,
               web::ExecuteJavaScript(manager_, @"cr.googleTranslate.libReady"));
 }