Update from https://crrev.com/312398

crypto/mock_apple_keychain.cc

 // Copyright (c) 2012 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.
 
 #include "base/logging.h"
+#include "base/metrics/histogram.h"
 #include "base/time/time.h"
 #include "crypto/mock_apple_keychain.h"
 
+namespace {
+
+// Adds an entry to a local histogram to indicate that the Apple Keychain would
+// have been accessed, if this class were not a mock of the Apple Keychain.
+void IncrementKeychainAccessHistogram() {
+  // This local histogram is accessed by Telemetry to track the number of times
+  // the keychain is accessed, since keychain access is known to be synchronous
+  // and slow.
+  LOCAL_HISTOGRAM_BOOLEAN("OSX.Keychain.Access", true);
+}
+
+}  // namespace
+
 namespace crypto {
 
 OSStatus MockAppleKeychain::FindGenericPassword(
     CFTypeRef keychainOrArray,
     UInt32 serviceNameLength,
     const char* serviceName,
     UInt32 accountNameLength,
     const char* accountName,
     UInt32* passwordLength,
     void** passwordData,
     SecKeychainItemRef* itemRef) const {
+  IncrementKeychainAccessHistogram();
+
   // When simulating |noErr|, return canned |passwordData| and
   // |passwordLength|.  Otherwise, just return given code.
   if (find_generic_result_ == noErr) {
     static const char kPassword[] = "my_password";
     DCHECK(passwordData);
     // The function to free this data is mocked so the cast is fine.
     *passwordData = const_cast<char*>(kPassword);
     DCHECK(passwordLength);
     *passwordLength = arraysize(kPassword);
     password_data_count_++;
@@ skipping 11 matching lines @@
 
 OSStatus MockAppleKeychain::AddGenericPassword(
     SecKeychainRef keychain,
     UInt32 serviceNameLength,
     const char* serviceName,
     UInt32 accountNameLength,
     const char* accountName,
     UInt32 passwordLength,
     const void* passwordData,
     SecKeychainItemRef* itemRef) const {
+  IncrementKeychainAccessHistogram();
+
   called_add_generic_ = true;
 
   DCHECK_GT(passwordLength, 0U);
   DCHECK(passwordData);
   add_generic_password_ =
       std::string(const_cast<char*>(static_cast<const char*>(passwordData)),
                   passwordLength);
   return noErr;
 }
 
+std::string MockAppleKeychain::GetEncryptionPassword() const {
+  IncrementKeychainAccessHistogram();
+  return "mock_password";
+}
+
 }  // namespace crypto