Chrome Version       : 52.0.2707.0
OS Version: OS X 10.11.3
URLs (if applicable) : http://www.ada.gov/emerprepguideprt.pdf

What steps will reproduce the problem?
1. Build chrome with DCHECKs enabled or debug
2. Open a PDF like above
3. Do a touchpad scroll (two finger scrolling)

What is the expected result?
The page should scroll

What happens instead of that?
The page scrolls a little but almost immediately crashes on a DCHECK

I commented out 2 and gave up after the third. Here's the DCHECKs that fired and their stack traces:


[9035:1295:0420/101004:FATAL:render_widget_host_impl.cc(1036)] Check failed: !(*is_in_gesture_scroll).
0   libbase.dylib                       0x000000011b2f4c2f _ZN4base5debug10StackTraceC2Ev + 47
1   libbase.dylib                       0x000000011b2f4dd3 _ZN4base5debug10StackTraceC1Ev + 35
2   libbase.dylib                       0x000000011b381a50 _ZN7logging10LogMessageD2Ev + 80
3   libbase.dylib                       0x000000011b37f383 _ZN7logging10LogMessageD1Ev + 35
4   libcontent.dylib                    0x000000011f39210c _ZN7content20RenderWidgetHostImpl34ForwardGestureEventWithLatencyInfoERKN5blink15WebGestureEventERKN2ui11LatencyInfoE + 636
5   libcontent.dylib                    0x000000011f391e5c _ZN7content20RenderWidgetHostImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 108
6   libcontent.dylib                    0x000000011f3924a2 _ZThn8_N7content20RenderWidgetHostImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 50
7   libcontent.dylib                    0x000000011f1a0529 _ZN7content15InputRouterImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 73
8   libcontent.dylib                    0x000000011f1a0582 _ZThn16_N7content15InputRouterImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 50
9   libcontent.dylib                    0x000000011f1ade7e _ZN7content20MouseWheelEventQueue15SendScrollBeginERKN5blink15WebGestureEventEb + 494
10  libcontent.dylib                    0x000000011f1ad8e5 _ZN7content20MouseWheelEventQueue20ProcessMouseWheelAckENS_18InputEventAckStateERKN2ui11LatencyInfoE + 2389
11  libcontent.dylib                    0x000000011f1a292a _ZN7content15InputRouterImpl15ProcessWheelAckENS_18InputEventAckStateERKN2ui11LatencyInfoE + 58
12  libcontent.dylib                    0x000000011f1a19a1 _ZN7content15InputRouterImpl20ProcessInputEventAckEN5blink13WebInputEvent4TypeENS_18InputEventAckStateERKN2ui11LatencyInfoEjNS0_9AckSourceE + 593
13  libcontent.dylib                    0x000000011f19e5c2 _ZN7content15InputRouterImpl15OnInputEventAckERKNS_13InputEventAckE + 770
14  libcontent.dylib                    0x000000011f1a82cf _ZN4base20DispatchToMethodImplIPN7content15InputRouterImplEMS2_FvRKNS1_13InputEventAckEEJS4_EJLm0EEEEvRKT_T0_RKNSt3__15tupleIJDpT1_EEENS_13IndexSequenceIJXspT2_EEEE + 175
15  libcontent.dylib                    0x000000011f1a81f3 _ZN4base16DispatchToMethodIPN7content15InputRouterImplEMS2_FvRKNS1_13InputEventAckEEJS4_EEEvRKT_T0_RKNSt3__15tupleIJDpT1_EEE + 83
16  libcontent.dylib                    0x000000011f1a7ffd _ZN3IPC16DispatchToMethodIN7content15InputRouterImplEMS2_FvRKNS1_13InputEventAckEEvNSt3__15tupleIJS3_EEEEEvPT_T0_PT1_RKT2_ + 93
17  libcontent.dylib                    0x000000011f19e240 _ZN3IPC8MessageTI38InputHostMsg_HandleInputEvent_ACK_MetaNSt3__15tupleIJN7content13InputEventAckEEEEvE8DispatchINS4_15InputRouterImplES9_vMS9_FvRKS5_EEEbPKNS_7MessageEPT_PT0_PT1_T2_ + 544
18  libcontent.dylib                    0x000000011f19da4a _ZN7content15InputRouterImpl17OnMessageReceivedERKN3IPC7MessageE + 474
19  libcontent.dylib                    0x000000011f3868fe _ZN7content20RenderWidgetHostImpl17OnMessageReceivedERKN3IPC7MessageE + 4702
20  libcontent.dylib                    0x000000011f38cfa2 _ZThn32_N7content20RenderWidgetHostImpl17OnMessageReceivedERKN3IPC7MessageE + 50
21  libcontent.dylib                    0x000000011f32d183 _ZN7content21RenderProcessHostImpl17OnMessageReceivedERKN3IPC7MessageE + 2179
22  libcontent.dylib                    0x000000011f32eb32 _ZThn8_N7content21RenderProcessHostImpl17OnMessageReceivedERKN3IPC7MessageE + 50
23  libipc.dylib                        0x0000000125e5c3c6 _ZN3IPC12ChannelProxy7Context17OnDispatchMessageERKNS_7MessageE + 166
24  libipc.dylib                        0x0000000125e62cec _ZN4base8internal15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS2_7MessageEEE3RunIS4_JS7_EEEvRK13scoped_refptrIT_EDpOT0_ + 156
25  libipc.dylib                        0x0000000125e62baa _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMN3IPC12ChannelProxy7ContextEFvRKNS3_7MessageEEEEE8MakeItSoIJRK13scoped_refptrIS5_ES8_EEEvSB_DpOT_ + 74


The next two DCHECKs seem to have fired at the same time (I'm guessing from different processes?):

[9076:18179:0420/101144:FATAL:input_handler_proxy.cc(591)] Check failed: !expect_scroll_update_end_.
0   libbase.dylib                       0x000000011b646c2f _ZN4base5debug10StackTraceC2Ev + 47
1   libbase.dylib                       0x000000011b646dd3 _ZN4base5debug10StackTraceC1Ev + 35
2   libbase.dylib                       0x000000011b6d3a50 _ZN7logging10LogMessageD2Ev + 80
3   libbase.dylib                       0x000000011b6d1383 _ZN7logging10LogMessageD1Ev + 35
4   libcontent.dylib                    0x0000000121015402 _ZN2ui17InputHandlerProxy24HandleGestureScrollBeginERKN5blink15WebGestureEventE + 274
5   libcontent.dylib                    0x0000000121013dc3 _ZN2ui17InputHandlerProxy16HandleInputEventERKN5blink13WebInputEventE + 403
6   libcontent.dylib                    0x000000012101313e _ZN2ui17InputHandlerProxy31HandleInputEventWithLatencyInfoERKN5blink13WebInputEventEPNS_11LatencyInfoE + 798
7   libcontent.dylib                    0x00000001203e5bfd _ZN7content19InputHandlerManager16HandleInputEventEiPKN5blink13WebInputEventEPN2ui11LatencyInfoE + 1501
8   libcontent.dylib                    0x00000001203e7aef _ZN4base8internal15RunnableAdapterIMN7content19InputHandlerManagerEFNS2_18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEEE3RunIJiS8_SB_EEES4_PS3_DpOT_ + 175
9   libcontent.dylib                    0x00000001203e79bd _ZN4base8internal12InvokeHelperILb0EN7content18InputEventAckStateENS0_15RunnableAdapterIMNS2_19InputHandlerManagerEFS3_iPKN5blink13WebInputEventEPN2ui11LatencyInfoEEEEE8MakeItSoIJPS5_iS9_SC_EEES3_SF_DpOT_ + 109
10  libcontent.dylib                    0x00000001203e7926 _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0EEEENS0_9BindStateINS0_15RunnableAdapterIMN7content19InputHandlerManagerEFNS6_18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEEEEFS8_PS7_iSC_SF_EJNS0_17UnretainedWrapperIS7_EEEEENS0_12InvokeHelperILb0ES8_SI_EEFS8_iSC_SF_EE3RunEPNS0_13BindStateBaseEOiOSC_OSF_ + 166
11  libcontent.dylib                    0x00000001203dbece _ZNK4base8CallbackIFN7content18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEELNS_8internal8CopyModeE1EE3RunEiS6_S9_ + 110
12  libcontent.dylib                    0x00000001203dad58 _ZN7content16InputEventFilter16ForwardToHandlerERKN3IPC7MessageE + 2264
13  libcontent.dylib                    0x00000001203dfe0c _ZN4base8internal15RunnableAdapterIMN7content16InputEventFilterEFvRKN3IPC7MessageEEE3RunIS3_JS7_EEEvRK13scoped_refptrIT_EDpOT0_ + 156
14  libcontent.dylib                    0x00000001203dfd0a _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMN7content16InputEventFilterEFvRKN3IPC7MessageEEEEE8MakeItSoIJRK13scoped_refptrIS4_ES8_EEEvSB_DpOT_ + 74
15  libcontent.dylib                    0x00000001203dfc9c _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0ELm1EEEENS0_9BindStateINS0_15RunnableAdapterIMN7content16InputEventFilterEFvRKN3IPC7MessageEEEEFvPS7_SB_EJSF_SB_EEENS0_12InvokeHelperILb0EvSE_EEFvvEE3RunEPNS0_13BindStateBaseE + 140


[9069:1295:0420/101144:FATAL:render_widget_host_impl.cc(1043)] Check failed: *is_in_gesture_scroll || (gesture_event.type == blink::WebInputEvent::GestureFlingStart && gesture_event.sourceDevice == blink::WebGestureDevice::WebGestureDeviceTouchpad).
0   libbase.dylib                       0x000000011b012c2f _ZN4base5debug10StackTraceC2Ev + 47
1   libbase.dylib                       0x000000011b012dd3 _ZN4base5debug10StackTraceC1Ev + 35
2   libbase.dylib                       0x000000011b09fa50 _ZN7logging10LogMessageD2Ev + 80
3   libbase.dylib                       0x000000011b09d383 _ZN7logging10LogMessageD1Ev + 35
4   libcontent.dylib                    0x000000011f0b024f _ZN7content20RenderWidgetHostImpl34ForwardGestureEventWithLatencyInfoERKN5blink15WebGestureEventERKN2ui11LatencyInfoE + 719
5   libcontent.dylib                    0x000000011f0aff4c _ZN7content20RenderWidgetHostImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 108
6   libcontent.dylib                    0x000000011f0b04d2 _ZThn8_N7content20RenderWidgetHostImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 50
7   libcontent.dylib                    0x000000011eebe619 _ZN7content15InputRouterImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 73
8   libcontent.dylib                    0x000000011eebe672 _ZThn16_N7content15InputRouterImpl19ForwardGestureEventERKN5blink15WebGestureEventE + 50
9   libcontent.dylib                    0x000000011eecc1eb _ZN7content20MouseWheelEventQueue13SendScrollEndEN5blink15WebGestureEventEb + 603
10  libcontent.dylib                    0x000000011eed235d _ZN4base8internal15RunnableAdapterIMN7content20MouseWheelEventQueueEFvN5blink15WebGestureEventEbEE3RunIJRKS5_RKbEEEvPS3_DpOT_ + 253
11  libcontent.dylib                    0x000000011eed21ad _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMN7content20MouseWheelEventQueueEFvN5blink15WebGestureEventEbEEEE8MakeItSoIJPS4_RKS6_RKbEEEvS9_DpOT_ + 93
12  libcontent.dylib                    0x000000011eed2130 _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0ELm1ELm2EEEENS0_9BindStateINS0_15RunnableAdapterIMN7content20MouseWheelEventQueueEFvN5blink15WebGestureEventEbEEEFvPS7_S9_bEJNS0_17UnretainedWrapperIS7_EERS9_bEEENS0_12InvokeHelperILb0EvSC_EEFvvEE3RunEPNS0_13BindStateBaseE + 192
13  libbase.dylib                       0x000000011afe8d4f _ZNK4base8CallbackIFvvELNS_8internal8CopyModeE1EE3RunEv + 63
14  libbase.dylib                       0x000000011b27473c _ZN4base5Timer16RunScheduledTaskEv + 284
15  libbase.dylib                       0x000000011b274517 _ZN4base21BaseTimerTaskInternal3RunEv + 87
16  libbase.dylib                       0x000000011b275217 _ZN4base8internal15RunnableAdapterIMNS_21BaseTimerTaskInternalEFvvEE3RunIJEEEvPS2_DpOT_ + 119
17  libbase.dylib                       0x000000011b27512d _ZN4base8internal12InvokeHelperILb0EvNS0_15RunnableAdapterIMNS_21BaseTimerTaskInternalEFvvEEEE8MakeItSoIJPS3_EEEvS6_DpOT_ + 61


And the final one:

[9104:18435:0420/101240:FATAL:input_handler_proxy.cc(591)] Check failed: !expect_scroll_update_end_.
0   libbase.dylib                       0x000000010e350c2f _ZN4base5debug10StackTraceC2Ev + 47
1   libbase.dylib                       0x000000010e350dd3 _ZN4base5debug10StackTraceC1Ev + 35
2   libbase.dylib                       0x000000010e3dda50 _ZN7logging10LogMessageD2Ev + 80
3   libbase.dylib                       0x000000010e3db383 _ZN7logging10LogMessageD1Ev + 35
4   libcontent.dylib                    0x0000000113d1f4c2 _ZN2ui17InputHandlerProxy24HandleGestureScrollBeginERKN5blink15WebGestureEventE + 274
5   libcontent.dylib                    0x0000000113d1de83 _ZN2ui17InputHandlerProxy16HandleInputEventERKN5blink13WebInputEventE + 403
6   libcontent.dylib                    0x0000000113d1d1fe _ZN2ui17InputHandlerProxy31HandleInputEventWithLatencyInfoERKN5blink13WebInputEventEPNS_11LatencyInfoE + 798
7   libcontent.dylib                    0x00000001130efcbd _ZN7content19InputHandlerManager16HandleInputEventEiPKN5blink13WebInputEventEPN2ui11LatencyInfoE + 1501
8   libcontent.dylib                    0x00000001130f1baf _ZN4base8internal15RunnableAdapterIMN7content19InputHandlerManagerEFNS2_18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEEE3RunIJiS8_SB_EEES4_PS3_DpOT_ + 175
9   libcontent.dylib                    0x00000001130f1a7d _ZN4base8internal12InvokeHelperILb0EN7content18InputEventAckStateENS0_15RunnableAdapterIMNS2_19InputHandlerManagerEFS3_iPKN5blink13WebInputEventEPN2ui11LatencyInfoEEEEE8MakeItSoIJPS5_iS9_SC_EEES3_SF_DpOT_ + 109
10  libcontent.dylib                    0x00000001130f19e6 _ZN4base8internal7InvokerINS_13IndexSequenceIJLm0EEEENS0_9BindStateINS0_15RunnableAdapterIMN7content19InputHandlerManagerEFNS6_18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEEEEFS8_PS7_iSC_SF_EJNS0_17UnretainedWrapperIS7_EEEEENS0_12InvokeHelperILb0ES8_SI_EEFS8_iSC_SF_EE3RunEPNS0_13BindStateBaseEOiOSC_OSF_ + 166
11  libcontent.dylib                    0x00000001130e5f8e _ZNK4base8CallbackIFN7content18InputEventAckStateEiPKN5blink13WebInputEventEPN2ui11LatencyInfoEELNS_8internal8CopyModeE1EE3RunEiS6_S9_ + 110
12  libcontent.dylib                    0x00000001130e4e18 _ZN7content16InputEventFilter16ForwardToHandlerERKN3IPC7MessageE + 2264
13  libcontent.dylib                    0x00000001130e9ecc _ZN4base8internal15RunnableAdapterIMN7content16InputEventFilterEFvRKN3IPC7MessageEEE3RunIS3_JS7_EEEvRK13scoped_refptrIT_EDpOT0_ + 156