Get maximum age of clipboard from clipboard_recent_contents.cc in iOS impl

components/open_from_clipboard/clipboard_recent_content_impl_ios.mm

 // Copyright 2017 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/open_from_clipboard/clipboard_recent_content_impl_ios.h"
 
 #import <CommonCrypto/CommonDigest.h>
 #import <UIKit/UIKit.h>
 
 #import "base/mac/foundation_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/sys_info.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 namespace {
 // Key used to store the pasteboard's current change count. If when resuming
 // chrome the pasteboard's change count is different from the stored one, then
 // it means that the pasteboard's content has changed.
 NSString* const kPasteboardChangeCountKey = @"PasteboardChangeCount";
 // Key used to store the last date at which it was detected that the pasteboard
 // changed. It is used to evaluate the age of the pasteboard's content.
 NSString* const kPasteboardChangeDateKey = @"PasteboardChangeDate";
 // Key used to store the hash of the content of the pasteboard. Whenever the
 // hash changed, the pasteboard content is considered to have changed.
 NSString* const kPasteboardEntryMD5Key = @"PasteboardEntryMD5";
-// Maximum age of clipboard in seconds.
-NSTimeInterval const kMaximumAgeOfClipboard = 3 * 60 * 60;
 
 // Compute a hash consisting of the first 4 bytes of the MD5 hash of |string|.
 // This value is used to detect pasteboard content change. Keeping only 4 bytes
 // is a privacy requirement to introduce collision and allow deniability of
 // having copied a given string.
 NSData* WeakMD5FromNSString(NSString* string) {
   unsigned char hash[CC_MD5_DIGEST_LENGTH];
   const std::string clipboard = base::SysNSStringToUTF8(string);
   const char* c_string = clipboard.c_str();
   CC_MD5(c_string, strlen(c_string), hash);
   NSData* data = [NSData dataWithBytes:hash length:4];
   return data;
 }
 
 }  // namespace
 
 @interface ClipboardRecentContentImplIOS ()
 
 // The user defaults from the app group used to optimize the pasteboard change
 // detection.
 @property(nonatomic, strong) NSUserDefaults* sharedUserDefaults;
 // The pasteboard's change count. Increases everytime the pasteboard changes.
 @property(nonatomic) NSInteger lastPasteboardChangeCount;
 // MD5 hash of the last registered pasteboard entry.
 @property(nonatomic, strong) NSData* lastPasteboardEntryMD5;
 // Contains the authorized schemes for URLs.
 @property(nonatomic, readonly) NSSet* authorizedSchemes;
 // Delegate for metrics.
 @property(nonatomic, strong) id<ClipboardRecentContentDelegate> delegate;
+// Maximum age of clipboard in seconds.
+@property(nonatomic) NSTimeInterval maximumAgeOfClipboard;

[marq (ping after 24h), 2017/04/13 11:33:38]

readonly, if this is only set in the init and never changes for the lifetime of
the object?

[lody, 2017/04/13 11:47:37]

Done.

 
 // If the content of the pasteboard has changed, updates the change count,
 // change date, and md5 of the latest pasteboard entry if necessary.
 - (void)updateIfNeeded;
 
 // Returns whether the pasteboard changed since the last time a pasteboard
 // change was detected.
 - (BOOL)hasPasteboardChanged;
 
 // Loads information from the user defaults about the latest pasteboard entry.
 - (void)loadFromUserDefaults;
 
 // Returns the URL contained in the clipboard (if any).
 - (NSURL*)URLFromPasteboard;
 
 // Returns the uptime.
 - (NSTimeInterval)uptime;
 
 @end
 
 @implementation ClipboardRecentContentImplIOS
 
 @synthesize lastPasteboardChangeCount = _lastPasteboardChangeCount;
 @synthesize lastPasteboardChangeDate = _lastPasteboardChangeDate;
 @synthesize lastPasteboardEntryMD5 = _lastPasteboardEntryMD5;
 @synthesize sharedUserDefaults = _sharedUserDefaults;
 @synthesize authorizedSchemes = _authorizedSchemes;
 @synthesize delegate = _delegate;
+@synthesize maximumAgeOfClipboard = _maximumAgeOfClipboard;
 
-- (instancetype)initWithAuthorizedSchemes:(NSSet<NSString*>*)authorizedSchemes
-                             userDefaults:(NSUserDefaults*)groupUserDefaults
-                                 delegate:(id<ClipboardRecentContentDelegate>)
-                                              delegate {
+- (instancetype)initWithMaxAge:(NSTimeInterval)maxAge
+             authorizedSchemes:(NSSet<NSString*>*)authorizedSchemes
+                  userDefaults:(NSUserDefaults*)groupUserDefaults
+                      delegate:(id<ClipboardRecentContentDelegate>)delegate {
   self = [super init];
   if (self) {
+    _maximumAgeOfClipboard = maxAge;
     _delegate = delegate;
     _authorizedSchemes = authorizedSchemes;
     _sharedUserDefaults = groupUserDefaults;
 
     _lastPasteboardChangeCount = NSIntegerMax;
     [self loadFromUserDefaults];
     [self updateIfNeeded];
 
     // Makes sure |last_pasteboard_change_count_| was properly initialized.
     DCHECK_NE(_lastPasteboardChangeCount, NSIntegerMax);
@@ skipping 38 matching lines @@
     return changeCountChanged;
   }
 
   BOOL md5Changed =
       ![[self getCurrentMD5] isEqualToData:self.lastPasteboardEntryMD5];
   return md5Changed;
 }
 
 - (NSURL*)recentURLFromClipboard {
   [self updateIfNeeded];
-  if ([self clipboardContentAge] > kMaximumAgeOfClipboard) {
+  if ([self clipboardContentAge] > [self maximumAgeOfClipboard]) {

[marq (ping after 24h), 2017/04/13 11:33:38]

Nit: prefer dot notation (self.maximumAgeOfClipboard) for properties.

[lody, 2017/04/13 11:47:37]

Done.

     return nil;
   }
   return [self URLFromPasteboard];
 }
 
 - (NSTimeInterval)clipboardContentAge {
   return -[self.lastPasteboardChangeDate timeIntervalSinceNow];
 }
 
 - (void)suppressClipboardContent {
@@ skipping 44 matching lines @@
                               forKey:kPasteboardChangeDateKey];
   [self.sharedUserDefaults setObject:self.lastPasteboardEntryMD5
                               forKey:kPasteboardEntryMD5Key];
 }
 
 - (NSTimeInterval)uptime {
   return base::SysInfo::Uptime().InSecondsF();
 }
 
 @end