Nice find. Reproduces on ChromeOS at least, probably elsewhere. From reading the description this seems really similar to issue 834598, where the second call to open() triggers activation.

I noticed that WebUSB dialog also triggers activation:
Here is the PoC: https://vulnerabledoma.in/popunder/webusb.html

onkeydown=function(){
    window.open('//example.com/','_blank','a');
}

onkeypress=function(){
    navigator.usb.requestDevice({filters:[]});
    location.href="//l0.cm/h_back.html"//do history.back()
}

Able to reproduce the issue on chrome reported version 68.0.3406.0 and on latest chrome 68.0.3409.2 using Mac 10.13.1, Win-10 and Ubuntu 14.04, as the same issue is seen from M-60(60.0.3112.0), hence considering this issue as non-regression and marking it as untriaged.

Thanks!

I split comment 3 into  bug 838314 . Please report one issue per bug entry.

The issue here is that closing a tab in a window activates the window.

AppKit`-[NSWindow makeKeyAndOrderFront:]
libcontent.dylib`content::WebContentsViewMac::Focus(this=0x0000000172309330) + 201 at web_contents_view_mac.mm:203
libcontent.dylib`content::WebContentsViewMac::SetInitialFocus(this=0x0000000172309330) + 134 at web_contents_view_mac.mm:213
libcontent.dylib`content::WebContentsViewMac::RestoreFocus(this=0x0000000172309330) + 92 at web_contents_view_mac.mm:230
libcontent.dylib`content::WebContentsImpl::RestoreFocus(this=0x0000000100894400) + 56 at web_contents_impl.cc:3320
libchrome_dll.dylib`::-[TabStripController activateTabWithContents:previousContents:atIndex:reason:](self=0x000000016581a460, _cmd="activateTabWithContents:previousContents:atIndex:reason:", newContents=0x0000000100894400, oldContents=0x00000001678b0000, modelIndex=1, reason=0) + 550 at tab_strip_controller.mm:1387
libchrome_dll.dylib`TabStripModelObserverBridge::ActiveTabChanged(this=0x0000000165803a30, old_contents=0x00000001678b0000, new_contents=0x0000000100894400, index=1, reason=0) + 118 at tab_strip_model_observer_bridge.mm:65
libchrome_dll.dylib`TabStripModel::NotifyIfActiveTabChanged(this=0x000000011c686800, old_contents=0x00000001678b0000, notify_types=kDefault) + 518 at tab_strip_model.cc:1205
libchrome_dll.dylib`TabStripModel::DetachWebContentsAt(this=0x000000011c686800, index=2) + 3976 at tab_strip_model.cc:332
libchrome_dll.dylib`TabStripModel::WebContentsData::WebContentsDestroyed(this=0x00000001723390b0) + 440 at tab_strip_model.cc:157
libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x00000001678b0000) + 4583 at web_contents_impl.cc:635
libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x00000001678b0000) + 21 at web_contents_impl.cc:547
libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x00000001678b0000) + 25 at web_contents_impl.cc:547
libchrome_dll.dylib`CloseWebContentses(delegate=0x000000011c686800, items=span<content::WebContents *const> @ 0x00007fff5fbfa948, close_types=2) + 914 at web_contents_closer.cc:152
libchrome_dll.dylib`TabStripModel::InternalCloseTabs(this=0x000000011c686800, items=span<content::WebContents *const> @ 0x00007fff5fbfaa98, close_types=2) + 407 at tab_strip_model.cc:1170
libchrome_dll.dylib`TabStripModel::CloseWebContentsAt(this=0x000000011c686800, index=2, close_types=2) + 288 at tab_strip_model.cc:460
libchrome_dll.dylib`chrome::CloseWebContents(browser=0x000000011c686500, contents=0x00000001678b0000, add_to_history=true) + 247 at browser_tabstrip.cc:81
libchrome_dll.dylib`Browser::CloseContents(this=0x000000011c686500, source=0x00000001678b0000) + 177 at browser.cc:1551
libcontent.dylib`content::WebContentsImpl::Close(this=0x00000001678b0000, rvh=0x0000000163bf7fa0) + 215 at web_contents_impl.cc:5195

And on Views we have the trace

  * frame #0: 0x00007fff82577f5c AppKit`-[NSWindow makeKeyAndOrderFront:]
    frame #1: 0x000000012262ad49 libcontent.dylib`content::WebContentsViewMac::Focus(this=0x000000015a4285b0) + 201 at web_contents_view_mac.mm:203
    frame #2: 0x00000001222150b8 libcontent.dylib`content::WebContentsImpl::Focus(this=0x0000000100811400) + 56 at web_contents_impl.cc:3308
    frame #3: 0x0000000139efdd63 libwebview.dylib`views::WebView::OnFocus(this=0x000000015a361010) + 131 at webview.cc:237
    frame #4: 0x000000013852728d libviews.dylib`views::View::Focus(this=0x000000015a361010) + 29 at view.cc:1801
    frame #5: 0x00000001384a9a27 libviews.dylib`views::FocusManager::SetFocusedViewWithReason(this=0x0000000162f7a090, view=0x000000015a361010, reason=kReasonDirectFocusChange) + 583 at focus_manager.cc:348
    frame #6: 0x0000000138389082 libviews.dylib`views::FocusManager::SetFocusedView(this=0x0000000162f7a090, view=0x000000015a361010) + 34 at focus_manager.h:175
    frame #7: 0x0000000138522d5e libviews.dylib`views::View::RequestFocus(this=0x000000015a361010) + 126 at view.cc:1313
    frame #8: 0x0000000139efe5f0 libwebview.dylib`views::WebView::OnWebContentsFocused(this=0x000000015a361010, render_widget_host=0x000000016583e200) + 32 at webview.cc:321
    frame #9: 0x0000000122208d1e libcontent.dylib`content::WebContentsImpl::NotifyWebContentsFocused(this=0x0000000100811400, render_widget_host=0x000000016583e200) + 158 at web_contents_impl.cc:3544
    frame #10: 0x000000012262b081 libcontent.dylib`content::WebContentsViewMac::GotFocus(this=0x000000015a4285b0, render_widget_host=0x000000016583e200) + 33 at web_contents_view_mac.mm:259
    frame #11: 0x0000000121ceeb84 libcontent.dylib`content::RenderViewHostImpl::RenderWidgetGotFocus(this=0x00000001639a3300) + 84 at render_view_host_impl.cc:697
    frame #12: 0x0000000121d034fa libcontent.dylib`content::RenderWidgetHostImpl::GotFocus(this=0x000000016583e200) + 58 at render_widget_host_impl.cc:903
    frame #13: 0x000000012261ca0c libcontent.dylib`content::RenderWidgetHostViewMac::OnNSViewIsFirstResponderChanged(this=0x000000016781e800, is_first_responder=true) + 108 at render_widget_host_view_mac.mm:1232
    frame #14: 0x00000001226412da libcontent.dylib`::-[RenderWidgetHostViewCocoa becomeFirstResponder](self=0x0000000163a1bde0, _cmd="becomeFirstResponder") + 186 at render_widget_host_view_cocoa.mm:1234
    frame #15: 0x00007fff824373fa AppKit`-[NSWindow _realMakeFirstResponder:] + 431
    frame #16: 0x00007fff824371f7 AppKit`-[NSWindow makeFirstResponder:] + 123
    frame #17: 0x000000012262ad0d libcontent.dylib`content::WebContentsViewMac::Focus(this=0x000000015a4285b0) + 141 at web_contents_view_mac.mm:200
    frame #18: 0x00000001222150b8 libcontent.dylib`content::WebContentsImpl::Focus(this=0x0000000100811400) + 56 at web_contents_impl.cc:3308
    frame #19: 0x0000000139efdd63 libwebview.dylib`views::WebView::OnFocus(this=0x000000015a361010) + 131 at webview.cc:237
    frame #20: 0x000000013852728d libviews.dylib`views::View::Focus(this=0x000000015a361010) + 29 at view.cc:1801
    frame #21: 0x00000001384a9a27 libviews.dylib`views::FocusManager::SetFocusedViewWithReason(this=0x0000000162f7a090, view=0x000000015a361010, reason=kReasonDirectFocusChange) + 583 at focus_manager.cc:348
    frame #22: 0x0000000138389082 libviews.dylib`views::FocusManager::SetFocusedView(this=0x0000000162f7a090, view=0x000000015a361010) + 34 at focus_manager.h:175
    frame #23: 0x0000000138522d5e libviews.dylib`views::View::RequestFocus(this=0x000000015a361010) + 126 at view.cc:1313
    frame #24: 0x000000010a3b47f8 libchrome_dll.dylib`ChromeWebContentsViewFocusHelper::RestoreFocus(this=0x000000015a427100) + 72 at chrome_web_contents_view_focus_helper.cc:68
    frame #25: 0x000000010a13844d libchrome_dll.dylib`ChromeWebContentsViewDelegateViewsMac::RestoreFocus(this=0x000000015a428460) + 29 at chrome_web_contents_view_delegate_views_mac.mm:38
    frame #26: 0x000000012262ae9d libcontent.dylib`content::WebContentsViewMac::RestoreFocus(this=0x000000015a4285b0) + 61 at web_contents_view_mac.mm:222
    frame #27: 0x0000000122215178 libcontent.dylib`content::WebContentsImpl::RestoreFocus(this=0x0000000100811400) + 56 at web_contents_impl.cc:3320
    frame #28: 0x000000010a328867 libchrome_dll.dylib`BrowserView::OnActiveTabChanged(this=0x0000000163014600, old_contents=0x000000015e0c3800, new_contents=0x0000000100811400, index=0, reason=0) + 1239 at browser_view.cc:821
    frame #29: 0x0000000109a8afb7 libchrome_dll.dylib`Browser::ActiveTabChanged(this=0x0000000162f743b0, old_contents=0x000000015e0c3800, new_contents=0x0000000100811400, index=0, reason=0) + 183 at browser.cc:1079
    frame #30: 0x0000000109bb2736 libchrome_dll.dylib`TabStripModel::NotifyIfActiveTabChanged(this=0x0000000162f746b0, old_contents=0x000000015e0c3800, notify_types=kDefault) + 518 at tab_strip_model.cc:1205
    frame #31: 0x0000000109badde8 libchrome_dll.dylib`TabStripModel::DetachWebContentsAt(this=0x0000000162f746b0, index=1) + 3976 at tab_strip_model.cc:332
    frame #32: 0x0000000109bacbe8 libchrome_dll.dylib`TabStripModel::WebContentsData::WebContentsDestroyed(this=0x0000000169f0aa30) + 440 at tab_strip_model.cc:157
    frame #33: 0x00000001221f29c7 libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x000000015e0c3800) + 4583 at web_contents_impl.cc:635
    frame #34: 0x00000001221f4635 libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x000000015e0c3800) + 21 at web_contents_impl.cc:547
    frame #35: 0x00000001221f4759 libcontent.dylib`content::WebContentsImpl::~WebContentsImpl(this=0x000000015e0c3800) + 25 at web_contents_impl.cc:547
    frame #36: 0x0000000109bcf172 libchrome_dll.dylib`CloseWebContentses(delegate=0x0000000162f746b0, items=span<content::WebContents *const> @ 0x00007fff5fbfa918, close_types=2) + 914 at web_contents_closer.cc:152
    frame #37: 0x0000000109bb5097 libchrome_dll.dylib`TabStripModel::InternalCloseTabs(this=0x0000000162f746b0, items=span<content::WebContents *const> @ 0x00007fff5fbfaa68, close_types=2) + 407 at tab_strip_model.cc:1170
    frame #38: 0x0000000109bb5380 libchrome_dll.dylib`TabStripModel::CloseWebContentsAt(this=0x0000000162f746b0, index=1, close_types=2) + 288 at tab_strip_model.cc:460
    frame #39: 0x0000000109acc2b7 libchrome_dll.dylib`chrome::CloseWebContents(browser=0x0000000162f743b0, contents=0x000000015e0c3800, add_to_history=true) + 247 at browser_tabstrip.cc:81
    frame #40: 0x0000000109a906b1 libchrome_dll.dylib`Browser::CloseContents(this=0x0000000162f743b0, source=0x000000015e0c3800) + 177 at browser.cc:1551