Don't count modifiers-changed events as being user gestures.

third_party/WebKit/Source/core/input/KeyboardEventManager.cpp

 // Copyright 2016 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.
 
 #include "KeyboardEventManager.h"
 
+#include <memory>
+
 #include "core/dom/DocumentUserGestureToken.h"
 #include "core/dom/Element.h"
 #include "core/editing/Editor.h"
 #include "core/events/KeyboardEvent.h"
 #include "core/frame/LocalFrameClient.h"
 #include "core/html/HTMLDialogElement.h"
 #include "core/input/EventHandler.h"
 #include "core/input/EventHandlingUtil.h"
 #include "core/input/InputDeviceCapabilities.h"
 #include "core/input/ScrollManager.h"
 #include "core/layout/LayoutObject.h"
 #include "core/layout/LayoutTextControlSingleLine.h"
 #include "core/page/ChromeClient.h"
 #include "core/page/FocusController.h"
 #include "core/page/Page.h"
 #include "core/page/SpatialNavigation.h"
 #include "platform/KeyboardCodes.h"
 #include "platform/UserGestureIndicator.h"
 #include "platform/WindowsKeyboardCodes.h"
+#include "public/platform/Platform.h"
 #include "public/platform/WebInputEvent.h"
 
 #if OS(WIN)
 #include <windows.h>
 #elif OS(MACOSX)
 #import <Carbon/Carbon.h>
 #endif
 
 namespace blink {
 
@@ skipping 144 matching lines @@
     // If we were in panscroll mode, we swallow the key event
     return WebInputEventResult::kHandledSuppressed;
   }
 
   // Check for cases where we are too early for events -- possible unmatched key
   // up from pressing return in the location bar.
   Node* node = EventTargetNodeForDocument(frame_->GetDocument());
   if (!node)
     return WebInputEventResult::kNotHandled;
 
-  UserGestureIndicator gesture_indicator(
-      DocumentUserGestureToken::Create(frame_->GetDocument()));
+  // To be meaningful enough to indicate user intention, a keyboard event needs
+  // - not to be a modifier event
+  // https://crbug.com/709765
+  bool is_modifier =
+      Platform::Current()->IsDomKeyForModifier(initial_key_event.dom_key);
+
+  std::unique_ptr<UserGestureIndicator> gesture_indicator;
+  if (!is_modifier) {
+    gesture_indicator.reset(new UserGestureIndicator(
+        DocumentUserGestureToken::Create(frame_->GetDocument())));
+  }
 
   // In IE, access keys are special, they are handled after default keydown
   // processing, but cannot be canceled - this is hard to match.  On Mac OS X,
   // we process them before dispatching keydown, as the default keydown handler
   // implements Emacs key bindings, which may conflict with access keys. Then we
   // dispatch keydown, but suppress its default handling.
   // On Windows, WebKit explicitly calls handleAccessKey() instead of
   // dispatching a keypress event for WM_SYSCHAR messages.  Other platforms
   // currently match either Mac or Windows behavior, depending on whether they
   // send combined KeyDown events.
@@ skipping 272 matching lines @@
   if (current_modifiers & ::cmdKey)
     modifiers |= WebInputEvent::kMetaKey;
 #else
   // TODO(crbug.com/538289): Implement on other platforms.
   return static_cast<WebInputEvent::Modifiers>(0);
 #endif
   return static_cast<WebInputEvent::Modifiers>(modifiers);
 }
 
 }  // namespace blink