I don't have reliable repro steps. I am reproing fairly easily by opening a few tabs on an iPad Pro with a keyboard and typing "asdf" in the omnibox and navigating to an SRP.
It seems like this may only happen when there is at least one incognito tab, but I'm not sure. 

Stack trace:
* thread #1, name = 'CrWebMain', queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x0000000181414500 libobjc.A.dylib`objc_exception_throw
    frame #1: 0x00000001829b2f28 CoreFoundation`+[NSException raise:format:] + 116
    frame #2: 0x00000001833a9660 Foundation`-[NSObject(NSKeyValueCoding) valueForKey:] + 360
    frame #3: 0x0000000185d36254 QuartzCore`CAObject_valueForKey + 140
    frame #4: 0x0000000188dbbc18 UIKit`-[_UIViewAdditiveAnimationAction runActionForKey:object:arguments:] + 1788
    frame #5: 0x0000000185cc410c QuartzCore`-[CALayer setContents:] + 256
    frame #6: 0x0000000188aecc74 UIKit`-[UIImageView _setImageViewContents:] + 1824
    frame #7: 0x0000000188aec0dc UIKit`-[UIImageView _updateState] + 664
    frame #8: 0x0000000188aedeb4 UIKit`-[UIImageView tintColorDidChange] + 140
    frame #9: 0x0000000188ff3224 UIKit`-[_UITintColorVisitor _visitView:] + 352
    frame #10: 0x0000000188ff3908 UIKit`_UIViewVisitorEntertainVisitors + 104
    frame #11: 0x0000000188ff2a3c UIKit`_UIViewVisitorRecursivelyEntertainDescendingVisitors + 196
    frame #12: 0x0000000188ff271c UIKit`+[_UIViewVisitor _startTraversalOfVisitor:withView:] + 332
    frame #13: 0x0000000188dc702c UIKit`-[UIView _dispatchTintColorVisitorWithReasons:] + 144
    frame #14: 0x0000000188b53c60 UIKit`-[UIView setTintColor:] + 120
    frame #15: 0x0000000188b134d8 UIKit`+[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 644
    frame #16: 0x0000000188b29bd0 UIKit`+[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:options:animations:completion:] + 108
    frame #17: 0x0000000188fd8cf4 UIKit`-[UIButton _updateImageView] + 968
    frame #18: 0x0000000188b32bb4 UIKit`-[UIButton layoutSubviews] + 192
  * frame #19: 0x0000000101418bc8 Chromium`::-[ToolbarButton layoutSubviews](self=0x000000011dd5c180, _cmd="layoutSubviews") at toolbar_button.mm:57
    frame #20: 0x0000000188adb178 UIKit`-[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1200
    frame #21: 0x0000000185ccb274 QuartzCore`-[CALayer layoutSublayers] + 148
    frame #22: 0x0000000185cbfde8 QuartzCore`CA::Layer::layout_if_needed(CA::Transaction*) + 292
    frame #23: 0x0000000188aef910 UIKit`-[UIView(Hierarchy) layoutBelowIfNeeded] + 548
    frame #24: 0x0000000101643450 Chromium`::-[PrimaryToolbarViewController contractLocationBar](self=0x000000011dd54860, _cmd="contractLocationBar") at primary_toolbar_view_controller.mm:187
    frame #25: 0x00000001016470dc Chromium`::__54-[OmniboxFocusOrchestrator updateUIToContractedState:]_block_invoke(.block_descriptor=0x0000000174e482b0) at omnibox_focus_orchestrator.mm:66
    frame #26: 0x000000018957c48c UIKit`-[UIViewPropertyAnimator _runAnimations] + 204
    frame #27: 0x0000000189582ccc UIKit`__41-[UIViewPropertyAnimator startAnimation:]_block_invoke + 304
    frame #28: 0x0000000189582220 UIKit`-[UIViewPropertyAnimator _setupAnimationTracking:] + 148
    frame #29: 0x00000001895829c0 UIKit`-[UIViewPropertyAnimator startAnimation:] + 1492
    frame #30: 0x0000000101646eac Chromium`::-[OmniboxFocusOrchestrator updateUIToContractedState:](self=0x00000001700172f0, _cmd="updateUIToContractedState:", animated=YES) at omnibox_focus_orchestrator.mm:95
    frame #31: 0x00000001016464c4 Chromium`::-[OmniboxFocusOrchestrator transitionToStateOmniboxFocused:toolbarExpanded:animated:](self=0x00000001700172f0, _cmd="transitionToStateOmniboxFocused:toolbarExpanded:animated:", omniboxFocused=YES, toolbarExpanded=NO, animated=YES) at omnibox_focus_orchestrator.mm:25
    frame #32: 0x000000010216be40 Chromium`::-[PrimaryToolbarCoordinator transitionToLocationBarFocusedState:](self=0x0000000170108ee0, _cmd="transitionToLocationBarFocusedState:", focused=YES) at primary_toolbar_coordinator.mm:124
    frame #33: 0x0000000101dd7ffc Chromium`::-[BrowserViewController locationBarDidBecomeFirstResponder](self=0x000000011e844400, _cmd="locationBarDidBecomeFirstResponder") at browser_view_controller.mm:4399
    frame #34: 0x0000000101539da0 Chromium`::-[LocationBarCoordinator locationBarHasBecomeFirstResponder](self=0x00000001700d2bb0, _cmd="locationBarHasBecomeFirstResponder") at location_bar_coordinator.mm:245
    frame #35: 0x0000000101401b98 Chromium`WebOmniboxEditControllerImpl::OnSetFocus(this=0x00000001701296a0) at web_omnibox_edit_controller_impl.mm:35
    frame #36: 0x00000001013fb690 Chromium`OmniboxViewIOS::OnDidBeginEditing(this=0x00000001701f2000) at omnibox_view_ios.mm:436
    frame #37: 0x00000001013fb390 Chromium`::-[AutocompleteTextFieldDelegate textFieldDidBeginEditing:](self=0x0000000174035de0, _cmd="textFieldDidBeginEditing:", textField=0x000000011e0a4a00) at omnibox_view_ios.mm:134
    frame #38: 0x0000000188be3f1c UIKit`-[UITextField _becomeFirstResponder] + 644
    frame #39: 0x0000000188b61578 UIKit`-[UIResponder becomeFirstResponder] + 388
    frame #40: 0x0000000188b619bc UIKit`-[UIView(Hierarchy) becomeFirstResponder] + 148
    frame #41: 0x0000000188be2930 UIKit`-[UITextField becomeFirstResponder] + 64
    frame #42: 0x00000001013e33f8 Chromium`::-[ClippingTextField becomeFirstResponder](self=0x000000011e0a4a00, _cmd="becomeFirstResponder") at clipping_textfield.mm:25
    frame #43: 0x00000001013eb158 Chromium`::-[OmniboxCoordinator focusOmnibox](self=0x0000000170474100, _cmd="focusOmnibox") at omnibox_coordinator.mm:96
    frame #44: 0x0000000101539c68 Chromium`::-[LocationBarCoordinator focusOmnibox](self=0x00000001700d2bb0, _cmd="focusOmnibox") at location_bar_coordinator.mm:235
    frame #45: 0x0000000101ddafd0 Chromium`::__36-[BrowserViewController openNewTab:]_block_invoke(.block_descriptor=0x0000000178091170) at browser_view_controller.mm:4592
    frame #46: 0x0000000101de145c Chromium`::__62-[BrowserViewController tabModel:newTabWillOpen:inBackground:]_block_invoke(.block_descriptor=0x0000000178a45e50) at browser_view_controller.mm:5026
    frame #47: 0x000000010cc89a50 libdispatch.dylib`_dispatch_call_block_and_release + 24
    frame #48: 0x000000010cc89a10 libdispatch.dylib`_dispatch_client_callout + 16
    frame #49: 0x000000010cc8eb78 libdispatch.dylib`_dispatch_main_queue_callback_4CF + 1204
    frame #50: 0x00000001829610c8 CoreFoundation`__CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 12
    frame #51: 0x000000018295ece4 CoreFoundation`__CFRunLoopRun + 1572
    frame #52: 0x000000018288eda4 CoreFoundation`CFRunLoopRunSpecific + 424
    frame #53: 0x00000001842f9074 GraphicsServices`GSEventRunModal + 100
    frame #54: 0x0000000188b43154 UIKit`UIApplicationMain + 208
    frame #55: 0x00000001000c32fc Chromium`(anonymous namespace)::RunUIApplicationMain(argc=1, argv=0x000000016fd43a98) at chrome_exe_main.mm:54
    frame #56: 0x00000001000c2d1c Chromium`main(argc=1, argv=0x000000016fd43a98) at chrome_exe_main.mm:78
    frame #57: 0x000000018189d59c libdyld.dylib`start + 4