Remove the CHECK from the DirectManipulationHelper::Activate function as it is firing in Canary on …

ui/views/win/hwnd_message_handler.cc

 // Copyright (c) 2012 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 "ui/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 
@@ skipping 623 matching lines @@
 
 void HWNDMessageHandler::Hide() {
   if (IsWindow(hwnd())) {
     // NOTE: Be careful not to activate any windows here (for example, calling
     // ShowWindow(SW_HIDE) will automatically activate another window).  This
     // code can be called while a window is being deactivated, and activating
     // another window will screw up the activation that is already in progress.
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0,
                  SWP_HIDEWINDOW | SWP_NOACTIVATE | SWP_NOMOVE |
                  SWP_NOREPOSITION | SWP_NOSIZE | SWP_NOZORDER);
+
+    if (direct_manipulation_helper_)
+      direct_manipulation_helper_->Deactivate(hwnd());
   }
 }
 
 void HWNDMessageHandler::Maximize() {
   ExecuteSystemMenuCommand(SC_MAXIMIZE);
 }
 
 void HWNDMessageHandler::Minimize() {
   ExecuteSystemMenuCommand(SC_MINIMIZE);
   delegate_->HandleNativeBlur(NULL);
@@ skipping 1845 matching lines @@
   }
 
   if (window_pos->flags & SWP_SHOWWINDOW)
     delegate_->HandleVisibilityChanging(true);
   else if (window_pos->flags & SWP_HIDEWINDOW)
     delegate_->HandleVisibilityChanging(false);
 
   SetMsgHandled(FALSE);
 }
 
 void HWNDMessageHandler::OnWindowPosChanged(WINDOWPOS* window_pos) {

[sky, 2015/08/14 14:55:26]

Wouldn't it be safer to do the Activate/Deactivate here? Same comment for
LegacyRenderWidgetHostHWND. Also, do the activate/deactivate calls need to be
balanced?

[ananta, 2015/08/14 18:39:02]

It shouldn't matter I think. We are calling Activate/Deactivate after the
ShowWindow call. From what I could see in the disassembly Activate bails if the
window is already active and same with Deactivate. 
So I think we are fine.

[sky, 2015/08/14 20:03:36]

Yes, but might the system hide/show a window behind the scenes? Say you right
click on the window icon and hide?

[ananta, 2015/08/14 20:33:47]

Fair enough. Done

   // TODO(vadimt): Remove ScopedTracker below once crbug.com/440919 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "440919 HWNDMessageHandler::OnWindowPosChanged"));
 
   if (DidClientAreaSizeChange(window_pos))
     ClientAreaSizeChanged();
   if (remove_standard_frame_ && window_pos->flags & SWP_FRAMECHANGED &&
       ui::win::IsAeroGlassEnabled() &&
       (window_ex_style() & WS_EX_COMPOSITED) == 0) {
@@ skipping 259 matching lines @@
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_HIDEWINDOW);
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_SHOWWINDOW);
   }
   // WM_DWMCOMPOSITIONCHANGED is only sent to top level windows, however we want
   // to notify our children too, since we can have MDI child windows who need to
   // update their appearance.
   EnumChildWindows(hwnd(), &SendDwmCompositionChanged, NULL);
 }
 
 }  // namespace views