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

content/browser/renderer_host/legacy_render_widget_host_win.cc

 // Copyright (c) 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.
 
 #include "content/browser/renderer_host/legacy_render_widget_host_win.h"
 
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/win/windows_version.h"
 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
@@ skipping 58 matching lines @@
     ::EnableWindow(hwnd(), TRUE);
   }
 }
 
 HWND LegacyRenderWidgetHostHWND::GetParent() {
   return ::GetParent(hwnd());
 }
 
 void LegacyRenderWidgetHostHWND::Show() {
   ::ShowWindow(hwnd(), SW_SHOW);
-  if (direct_manipulation_helper_)
-    direct_manipulation_helper_->Activate(hwnd());
 }
 
 void LegacyRenderWidgetHostHWND::Hide() {
   ::ShowWindow(hwnd(), SW_HIDE);
 }
 
 void LegacyRenderWidgetHostHWND::SetBounds(const gfx::Rect& bounds) {
   gfx::Rect bounds_in_pixel = gfx::win::DIPToScreenRect(bounds);
   ::SetWindowPos(hwnd(), NULL, bounds_in_pixel.x(), bounds_in_pixel.y(),
                  bounds_in_pixel.width(), bounds_in_pixel.height(),
@@ skipping 299 matching lines @@
   // Additionally others check if the window WS_VSCROLL/WS_HSCROLL styles and
   // generate the legacy WM_VSCROLL/WM_HSCROLL messages.
   // We add these styles to ensure that trackpad/trackpoint scrolling
   // work.
   long current_style = ::GetWindowLong(hwnd(), GWL_STYLE);
   ::SetWindowLong(hwnd(), GWL_STYLE,
                   current_style | WS_VSCROLL | WS_HSCROLL);
   return 0;
 }
 
+LRESULT LegacyRenderWidgetHostHWND::OnWindowPosChanged(UINT message,
+                                                       WPARAM w_param,
+                                                       LPARAM l_param) {
+  WINDOWPOS* window_pos = reinterpret_cast<WINDOWPOS*>(l_param);
+  if (direct_manipulation_helper_) {
+    if (window_pos->flags & SWP_SHOWWINDOW) {
+      direct_manipulation_helper_->Activate(hwnd());
+    } else if (window_pos->flags & SWP_HIDEWINDOW) {
+      direct_manipulation_helper_->Deactivate(hwnd());
+    }
+  }
+  return 0;

[sky, 2015/08/14 20:56:37]

Do you need the SetMsgHandled(FALSE); ?

[ananta, 2015/08/14 21:04:30]

Done. 

+}
+
 }  // namespace content