MacViews: Fix window dragging on Sierra.

ui/views/cocoa/native_widget_mac_nswindow.mm

 // Copyright 2014 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.
 
 #import "ui/views/cocoa/native_widget_mac_nswindow.h"
 
 #include "base/mac/foundation_util.h"
+#include "base/mac/sdk_forward_declarations.h"
 #import "ui/views/cocoa/bridged_native_widget.h"
 #import "ui/base/cocoa/user_interface_item_command_handler.h"
 #import "ui/views/cocoa/views_nswindow_delegate.h"
 #include "ui/views/controls/menu/menu_controller.h"
 #include "ui/views/widget/native_widget_mac.h"
 #include "ui/views/widget/widget_delegate.h"
 
 @interface NSWindow (Private)
 - (BOOL)hasKeyAppearance;
 @end
@@ skipping 82 matching lines @@
          !views::NativeWidgetMac::GetBridgeForNativeWindow(self)->parent();
 }
 
 // Lets the traffic light buttons on the parent window keep their active state.
 - (BOOL)hasKeyAppearance {
   if ([self delegate] && [self viewsWidget]->IsAlwaysRenderAsActive())
     return YES;
   return [super hasKeyAppearance];
 }
 
-// Override sendEvent to allow key events to be forwarded to a toolkit-views
-// menu while it is active, and while still allowing any native subview to
-// retain firstResponder status.
+// Override sendEvent to intercept window drag events and allow key events to be
+// forwarded to a toolkit-views menu while it is active, and while still
+// allowing any native subview to retain firstResponder status.
 - (void)sendEvent:(NSEvent*)event {
   // Let CommandDispatcher check if this is a redispatched event.
   if ([commandDispatcher_ preSendEvent:event])
     return;
 
+  // If a window drag event monitor is not used, query the BridgedNativeWidget
+  // to decide if a window drag should be performed.
+  if (!views::BridgedNativeWidget::ShouldUseDragEventMonitor()) {
+    views::BridgedNativeWidget* bridge =
+        views::NativeWidgetMac::GetBridgeForNativeWindow(self);
+
+    if (bridge && bridge->ShouldDragWindow(event)) {
+      [self performWindowDragWithEvent:event];
+      return;
+    }
+  }
+
   NSEventType type = [event type];
   if ((type != NSKeyDown && type != NSKeyUp) || ![self hasViewsMenuActive]) {
     [super sendEvent:event];
     return;
   }
 
   // Send to the menu, after converting the event into an action message using
   // the content view.
   if (type == NSKeyDown)
     [[self contentView] keyDown:event];
@@ skipping 73 matching lines @@
     id appController = [NSApp delegate];
     DCHECK([appController
         conformsToProtocol:@protocol(NSUserInterfaceValidations)]);
     return [appController validateUserInterfaceItem:item];
   }
 
   return [super validateUserInterfaceItem:item];
 }
 
 @end