Chrome Version       : 56.0.2887.0ish r424259
OS Version: OS X 10.11.6

(found this while playing around with the "unknown subview" stuff, but I don't think it's related to that)

What steps will reproduce the problem?
1. In a build with DCHECKs
2. Go to http://rip747.github.io/popupwindow/ and Click "Example 1"
3. Click green fullscreen button or press Cmd+Ctrl+f (or menu -> enter fullscreen)
4. Press Cmd+Ctrl+f to exit fullscreen (or menu -> exit fullscreen)

What is the expected result?

No DCHECK/crash

What happens instead of that?

[53655:775:1013/094447:FATAL:browser_window_fullscreen_transition.mm(531)] Check failed: NSHeight(content.frame) == expectedSize.height (629 vs. 651)
* thread #1: tid = 0x4b5ab4, 0x0000000115d86e34 libbase.dylib`base::debug::BreakDebugger() + 20 at debugger_posix.cc:260, name = 'CrBrowserMain', queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=EXC_I386_BPT, subcode=0x0)
  * frame #0: 0x0000000115d86e34 libbase.dylib`base::debug::BreakDebugger() + 20 at debugger_posix.cc:260
    frame #1: 0x0000000115e3297e libbase.dylib`logging::LogMessage::~LogMessage(this=0x00007fff5fbfca90) + 4302 at logging.cc:748
    frame #2: 0x0000000115e2f4b5 libbase.dylib`logging::LogMessage::~LogMessage(this=0x00007fff5fbfca90) + 21 at logging.cc:528
    frame #3: 0x000000010979d547 libchrome_dll.dylib`::-[BrowserWindowFullscreenTransition animationDidStop:finished:](self=0x000000013b5e3390, _cmd="animationDidStop:finished:", theAnimation=0x000000013b638fa0, finished=YES) + 1351 at browser_window_fullscreen_transition.mm:531
    frame #4: 0x00007fff91a3ac10 QuartzCore`CA::Layer::run_animation_callbacks(void*) + 308
    frame #5: 0x00007fff9567640b libdispatch.dylib`_dispatch_client_callout + 8
    frame #6: 0x00007fff95689c1c libdispatch.dylib`_dispatch_main_queue_callback_4CF + 1685
    frame #7: 0x00007fff89eae9e9 CoreFoundation`__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
    frame #8: 0x00007fff89e6d8dd CoreFoundation`__CFRunLoopRun + 1949
    frame #9: 0x00007fff89e6ced8 CoreFoundation`CFRunLoopRunSpecific + 296
    frame #10: 0x00007fff89a86935 HIToolbox`RunCurrentEventLoopInMode + 235
    frame #11: 0x00007fff89a8676f HIToolbox`ReceiveNextEventCommon + 432
    frame #12: 0x00007fff89a865af HIToolbox`_BlockUntilNextEventMatchingListInModeWithFilter + 71
    frame #13: 0x00007fff91e1edf6 AppKit`_DPSNextEvent + 1067
    frame #14: 0x00007fff91e1e226 AppKit`-[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 454
    frame #15: 0x00007fff91e12d80 AppKit`-[NSApplication run] + 682


frame #3: 0x000000010979d547 libchrome_dll.dylib`::-[BrowserWindowFullscreenTransition animationDidStop:finished:](self=0x000000013b5e3390, _cmd="animationDidStop:finished:", theAnimation=0x000000013b638fa0, finished=YES) + 1351 at browser_window_fullscreen_transition.mm:531
   528 	    // This will create a small janky movement at the end of the animation.
   529 	    NSSize expectedSize = finalFrame_.size;
   530 	    NSView* content = [primaryWindow_ contentView];
-> 531 	    DCHECK_EQ(NSHeight(content.frame), expectedSize.height);
   532 	    DCHECK_EQ(NSWidth(content.frame), expectedSize.width);
   533
   534 	    // Restore the state of the primary window and make it visible again.



UserAgentString: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2873.4 Safari/537.36