Revert "Create only a single LegacyRenderWidgetHostHWND per WebContentsViewAura."

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index bad6fbc9ba255eb49a636f19e829412978381da8..6a9a42080067950e1e3922c3ca1b6b2b9ae9ef28 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -448,6 +448,7 @@ RenderWidgetHostViewAura::RenderWidgetHostViewAura(RenderWidgetHost* host,
       cursor_visibility_state_in_renderer_(UNKNOWN),
 #if defined(OS_WIN)
       legacy_render_widget_host_HWND_(NULL),
+      legacy_window_destroyed_(false),
 #endif
       has_snapped_to_boundary_(false),
       touch_editing_client_(NULL),
@@ -601,6 +602,16 @@ void RenderWidgetHostViewAura::WasShown() {
   delegated_frame_host_->WasShown(browser_latency_info);
 
 #if defined(OS_WIN)
+  if (legacy_render_widget_host_HWND_) {
+    // Reparent the legacy Chrome_RenderWidgetHostHWND window to the parent
+    // window before reparenting any plugins. This ensures that the plugin
+    // windows stay on top of the child Zorder in the parent and receive
+    // mouse events, etc.
+    legacy_render_widget_host_HWND_->UpdateParent(
+        GetNativeView()->GetHost()->GetAcceleratedWidget());
+    legacy_render_widget_host_HWND_->SetBounds(
+        window_->GetBoundsInRootWindow());
+  }
   LPARAM lparam = reinterpret_cast<LPARAM>(this);
   EnumChildWindows(ui::GetHiddenWindow(), ShowWindowsCallback, lparam);
 #endif
@@ -619,6 +630,10 @@ void RenderWidgetHostViewAura::WasHidden() {
     HWND parent = host->GetAcceleratedWidget();
     LPARAM lparam = reinterpret_cast<LPARAM>(this);
     EnumChildWindows(parent, HideWindowsCallback, lparam);
+    // We reparent the legacy Chrome_RenderWidgetHostHWND window to the global
+    // hidden window on the same lines as Windowed plugin windows.
+    if (legacy_render_widget_host_HWND_)
+      legacy_render_widget_host_HWND_->UpdateParent(ui::GetHiddenWindow());
   }
 #endif
 }
@@ -782,11 +797,19 @@ bool RenderWidgetHostViewAura::IsSurfaceAvailableForCopy() const {
 void RenderWidgetHostViewAura::Show() {
   window_->Show();
   WasShown();
+#if defined(OS_WIN)
+  if (legacy_render_widget_host_HWND_)
+    legacy_render_widget_host_HWND_->Show();
+#endif
 }
 
 void RenderWidgetHostViewAura::Hide() {
   window_->Hide();
   WasHidden();
+#if defined(OS_WIN)
+  if (legacy_render_widget_host_HWND_)
+    legacy_render_widget_host_HWND_->Hide();
+#endif
 }
 
 bool RenderWidgetHostViewAura::IsShowing() {
@@ -1038,7 +1061,12 @@ void RenderWidgetHostViewAura::UpdateMouseLockRegion() {
     ::ClipCursor(&window_rect);
   }
 }
-#endif  // defined(OS_WIN)
+
+void RenderWidgetHostViewAura::OnLegacyWindowDestroyed() {
+  legacy_render_widget_host_HWND_ = NULL;
+  legacy_window_destroyed_ = true;
+}
+#endif
 
 void RenderWidgetHostViewAura::OnSwapCompositorFrame(
     uint32 output_surface_id,
@@ -1070,11 +1098,6 @@ void RenderWidgetHostViewAura::DidStopFlinging() {
 }
 
 #if defined(OS_WIN)
-void RenderWidgetHostViewAura::SetLegacyRenderWidgetHostHWND(
-    LegacyRenderWidgetHostHWND* legacy_hwnd) {
-  legacy_render_widget_host_HWND_ = legacy_hwnd;
-}
-
 void RenderWidgetHostViewAura::SetParentNativeViewAccessible(
     gfx::NativeViewAccessible accessible_parent) {
 }
@@ -1082,9 +1105,8 @@ void RenderWidgetHostViewAura::SetParentNativeViewAccessible(
 gfx::NativeViewId RenderWidgetHostViewAura::GetParentForWindowlessPlugin()
     const {
   if (legacy_render_widget_host_HWND_) {
-    HWND hwnd = legacy_render_widget_host_HWND_->hwnd();
-    if (::IsWindow(hwnd))
-      return reinterpret_cast<gfx::NativeViewId>(hwnd);
+    return reinterpret_cast<gfx::NativeViewId>(
+        legacy_render_widget_host_HWND_->hwnd());
   }
   return NULL;
 }
@@ -1227,11 +1249,8 @@ RenderWidgetHostViewAura::CreateBrowserAccessibilityManager(
 gfx::AcceleratedWidget
 RenderWidgetHostViewAura::AccessibilityGetAcceleratedWidget() {
 #if defined(OS_WIN)
-  if (legacy_render_widget_host_HWND_) {
-    HWND hwnd = legacy_render_widget_host_HWND_->hwnd();
-    if (::IsWindow(hwnd))
-      return hwnd;
-  }
+  if (legacy_render_widget_host_HWND_)
+    return legacy_render_widget_host_HWND_->hwnd();
 #endif
   return gfx::kNullAcceleratedWidget;
 }
@@ -1763,7 +1782,20 @@ void RenderWidgetHostViewAura::OnWindowDestroying(aura::Window* window) {
   }
   LPARAM lparam = reinterpret_cast<LPARAM>(this);
   EnumChildWindows(parent, WindowDestroyingCallback, lparam);
-  legacy_render_widget_host_HWND_ = NULL;
+
+  // The LegacyRenderWidgetHostHWND instance is destroyed when its window is
+  // destroyed. Normally we control when that happens via the Destroy call
+  // in the dtor. However there may be cases where the window is destroyed
+  // by Windows, i.e. the parent window is destroyed before the
+  // RenderWidgetHostViewAura instance goes away etc. To avoid that we
+  // destroy the LegacyRenderWidgetHostHWND instance here.
+  if (legacy_render_widget_host_HWND_) {
+    legacy_render_widget_host_HWND_->set_host(NULL);
+    legacy_render_widget_host_HWND_->Destroy();
+    // The Destroy call above will delete the LegacyRenderWidgetHostHWND
+    // instance.
+    legacy_render_widget_host_HWND_ = NULL;
+  }
 #endif
 
   // Make sure that the input method no longer references to this object before
@@ -2264,6 +2296,13 @@ RenderWidgetHostViewAura::~RenderWidgetHostViewAura() {
   // Aura root window and we don't have a way to get an input method object
   // associated with the window, but just in case.
   DetachFromInputMethod();
+
+#if defined(OS_WIN)
+  // The LegacyRenderWidgetHostHWND window should have been destroyed in
+  // RenderWidgetHostViewAura::OnWindowDestroying and the pointer should
+  // be set to NULL.
+  DCHECK(!legacy_render_widget_host_HWND_);
+#endif
 }
 
 void RenderWidgetHostViewAura::UpdateCursorIfOverSelf() {
@@ -2420,6 +2459,34 @@ void RenderWidgetHostViewAura::InternalSetBounds(const gfx::Rect& rect) {
                                                       selection_focus_);
   }
 #if defined(OS_WIN)
+  // Create the legacy dummy window which corresponds to the bounds of the
+  // webcontents. This will be passed as the container window for windowless
+  // plugins.
+  // Plugins like Flash assume the container window which is returned via the
+  // NPNVnetscapeWindow property corresponds to the bounds of the webpage.
+  // This is not true in Aura where we have only HWND which is the main Aura
+  // window. If we return this window to plugins like Flash then it causes the
+  // coordinate translations done by these plugins to break.
+  // Additonally the legacy dummy window is needed for accessibility and for
+  // scrolling to work in legacy drivers for trackpoints/trackpads, etc.
+  if (!legacy_window_destroyed_ && GetNativeViewId()) {
+    if (!legacy_render_widget_host_HWND_) {
+      legacy_render_widget_host_HWND_ = LegacyRenderWidgetHostHWND::Create(
+          reinterpret_cast<HWND>(GetNativeViewId()));
+    }
+    if (legacy_render_widget_host_HWND_) {
+      legacy_render_widget_host_HWND_->set_host(this);
+      legacy_render_widget_host_HWND_->SetBounds(
+          window_->GetBoundsInRootWindow());
+      // There are cases where the parent window is created, made visible and
+      // the associated RenderWidget is also visible before the
+      // LegacyRenderWidgetHostHWND instace is created. Ensure that it is shown
+      // here.
+      if (!host_->is_hidden())
+        legacy_render_widget_host_HWND_->Show();
+    }
+  }
+
   if (mouse_locked_)
     UpdateMouseLockRegion();
 #endif
@@ -2465,6 +2532,14 @@ void RenderWidgetHostViewAura::AddedToRootWindow() {
       input_method->SetFocusedTextInputClient(this);
   }
 
+#if defined(OS_WIN)
+  // The parent may have changed here. Ensure that the legacy window is
+  // reparented accordingly.
+  if (legacy_render_widget_host_HWND_)
+    legacy_render_widget_host_HWND_->UpdateParent(
+        reinterpret_cast<HWND>(GetNativeViewId()));
+#endif
+
   delegated_frame_host_->AddedToWindow();
 }
 
@@ -2478,6 +2553,13 @@ void RenderWidgetHostViewAura::RemovingFromRootWindow() {
 
   window_->GetHost()->RemoveObserver(this);
   delegated_frame_host_->RemovingFromWindow();
+
+#if defined(OS_WIN)
+  // Update the legacy window's parent temporarily to the desktop window. It
+  // will eventually get reparented to the right root.
+  if (legacy_render_widget_host_HWND_)
+    legacy_render_widget_host_HWND_->UpdateParent(::GetDesktopWindow());
+#endif
 }
 
 void RenderWidgetHostViewAura::DetachFromInputMethod() {