Ensure windows update when snapped to side on Windows 10.

It's possible to get a message that the window pos is changing, but have the window pos not actually change in the end. In this case, force the compositor to re-enable swapping.

BUG=516234
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1305363002

Cr-Commit-Position: refs/heads/master@{#347070}
(cherry picked from commit 55b4c95889d6a72e52bc72702580a62f04f35777)
TBR=sky@chromium.org

Review URL: https://codereview.chromium.org/1323333005 .

Cr-Commit-Position: refs/branch-heads/2454@{#452}
Cr-Branched-From: 12bfc3360892ec53cd00fc239a47e5298beb063b-refs/heads/master@{#338390}

5 files changed, 25 insertions, 2 deletions

diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
index 93b3c5b..9278c29 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc
@@ -906,6 +906,16 @@ void DesktopWindowTreeHostWin::HandleWindowSizeChanging() {
     compositor()->DisableSwapUntilResize();
 }
 
+void DesktopWindowTreeHostWin::HandleWindowSizeChanged() {
+  // A resize may not have occurred if the window size happened not to have
+  // changed (can occur on Windows 10 when snapping a window to the side of
+  // the screen). In that case do a resize to the current size to reenable
+  // swaps.
+  if (compositor())
+    compositor()->SetScaleAndSize(compositor()->device_scale_factor(),
+                                  compositor()->size());
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostWin, private:
 
diff --git a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.h b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
index c213ffe..047498f 100644
--- a/ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
+++ b/ui/views/widget/desktop_aura/desktop_window_tree_host_win.h
@@ -191,6 +191,7 @@ class VIEWS_EXPORT DesktopWindowTreeHostWin
   void PostHandleMSG(UINT message, WPARAM w_param, LPARAM l_param) override;
   bool HandleScrollEvent(const ui::ScrollEvent& event) override;
   void HandleWindowSizeChanging() override;
+  void HandleWindowSizeChanged() override;
 
   Widget* GetWidget();
   const Widget* GetWidget() const;
diff --git a/ui/views/win/hwnd_message_handler.cc b/ui/views/win/hwnd_message_handler.cc
index d223349..cf71db8 100644
--- a/ui/views/win/hwnd_message_handler.cc
+++ b/ui/views/win/hwnd_message_handler.cc
@@ -329,9 +329,9 @@ HWNDMessageHandler::HWNDMessageHandler(HWNDMessageHandlerDelegate* delegate)
       touch_down_contexts_(0),
       last_mouse_hwheel_time_(0),
       dwm_transition_desired_(false),
+      sent_window_size_changing_(false),
       autohide_factory_(this),
-      weak_factory_(this) {
-}
+      weak_factory_(this) {}
 
 HWNDMessageHandler::~HWNDMessageHandler() {
   delegate_ = NULL;
@@ -2470,6 +2470,7 @@ void HWNDMessageHandler::OnWindowPosChanging(WINDOWPOS* window_pos) {
   if ((old_size != new_size && !(window_pos->flags & SWP_NOSIZE)) ||
       window_pos->flags & SWP_FRAMECHANGED) {
     delegate_->HandleWindowSizeChanging();
+    sent_window_size_changing_ = true;
   }
 
   if (ScopedFullscreenVisibility::IsHiddenForFullscreen(hwnd())) {
@@ -2509,6 +2510,10 @@ void HWNDMessageHandler::OnWindowPosChanged(WINDOWPOS* window_pos) {
     if (direct_manipulation_helper_)
       direct_manipulation_helper_->Deactivate(hwnd());
   }
+  if (sent_window_size_changing_) {
+    sent_window_size_changing_ = false;
+    delegate_->HandleWindowSizeChanged();
+  }
   SetMsgHandled(FALSE);
 }
 
diff --git a/ui/views/win/hwnd_message_handler.h b/ui/views/win/hwnd_message_handler.h
index e7fc8af..6b8f719 100644
--- a/ui/views/win/hwnd_message_handler.h
+++ b/ui/views/win/hwnd_message_handler.h
@@ -584,6 +584,10 @@ class VIEWS_EXPORT HWNDMessageHandler :
   // glass. Defaults to false.
   bool dwm_transition_desired_;
 
+  // True if HandleWindowSizeChanging has been called in the delegate, but not
+  // HandleWindowSizeChanged.
+  bool sent_window_size_changing_;
+
   // Manages observation of Windows Session Change messages.
   scoped_ptr<WindowsSessionChangeObserver> windows_session_change_observer_;
 
diff --git a/ui/views/win/hwnd_message_handler_delegate.h b/ui/views/win/hwnd_message_handler_delegate.h
index e773b81..8f8957a 100644
--- a/ui/views/win/hwnd_message_handler_delegate.h
+++ b/ui/views/win/hwnd_message_handler_delegate.h
@@ -224,6 +224,9 @@ class VIEWS_EXPORT HWNDMessageHandlerDelegate {
   // Called when the window size is about to change.
   virtual void HandleWindowSizeChanging() = 0;
 
+  // Called when the window size has finished changing.
+  virtual void HandleWindowSizeChanged() = 0;
+
  protected:
   virtual ~HWNDMessageHandlerDelegate() {}
 };