Revert "Remove unneeded CursorLoaderWin::SetPlatformWindow calls"

This reverts commit 1208732e.

Reason for revert: likely making
ExecuteScriptApiTest.ExecuteScriptInFrame flaky.

Bug: 1131966

Original change's description:
> Remove unneeded CursorLoaderWin::SetPlatformWindow calls
>
> SetCursorNative is only called from WindowTreeHost::SetCursor, which
> guarantees that the platform cursor has been set.
>
> Bug: 1097556
> Change-Id: I4c140a872482ba33bf957ed6817279c275bf7f36
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2417893
> Reviewed-by: Scott Violet <sky@chromium.org>
> Commit-Queue: Henrique Ferreiro <hferreiro@igalia.com>
> Cr-Commit-Position: refs/heads/master@{#810120}

TBR=sky@chromium.org,hferreiro@igalia.com

Change-Id: I60d2de90149af77a5d6ebdce2f02a859f9262f9d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1097556
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2429229Reviewed-by: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Nina Satragno <nsatragno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#810251}

ui/aura/window_tree_host.cc

@@ -221,10 +221,6 @@ void WindowTreeHost::ConvertPixelsToDIP(gfx::Point* point) const {
 }
 
 void WindowTreeHost::SetCursor(gfx::NativeCursor cursor) {
-  // Some CursorFactory implementations use nullptr to represent the hidden
-  // cursor (i.e. cursor type kNone).
-  DCHECK(cursor.type() == ui::mojom::CursorType::kNone || cursor.platform());
-
   last_cursor_ = cursor;
   // A lot of code seems to depend on NULL cursors actually showing an arrow,
   // so just pass everything along to the host.

ui/aura/window_tree_host.h

@@ -136,12 +136,11 @@ class AURA_EXPORT WindowTreeHost : public ui::internal::InputMethodDelegate,
   // root window's.
   virtual void ConvertPixelsToDIP(gfx::Point* point) const;
 
+  // Cursor.
   // Sets the currently-displayed cursor. If the cursor was previously hidden
   // via ShowCursor(false), it will remain hidden until ShowCursor(true) is
   // called, at which point the cursor that was last set via SetCursor() will be
   // used.
-  // `cursor` should have its platform cursor set, e.g. via
-  // `CursorLoader::SetPlatformCursor`.
   void SetCursor(gfx::NativeCursor cursor);
 
   // Invoked when the cursor's visibility has changed.

ui/aura/window_tree_host_platform.cc

@@ -34,6 +34,7 @@
 #endif
 
 #if defined(OS_WIN)
+#include "ui/base/cursor/cursor_loader_win.h"
 #include "ui/platform_window/win/win_window.h"
 #endif
 
@@ -184,6 +185,11 @@ void WindowTreeHostPlatform::SetCursorNative(gfx::NativeCursor cursor) {
     return;
   current_cursor_ = cursor;
 
+#if defined(OS_WIN)
+  ui::CursorLoaderWin cursor_loader;
+  cursor_loader.SetPlatformCursor(&cursor);
+#endif
+
   platform_window_->SetCursor(cursor.platform());
 }
 

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

@@ -22,6 +22,7 @@
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/class_property.h"
+#include "ui/base/cursor/cursor_loader_win.h"
 #include "ui/base/ime/input_method.h"
 #include "ui/base/ui_base_features.h"
 #include "ui/base/win/event_creation_utils.h"
@@ -631,6 +632,9 @@ DesktopWindowTreeHostWin::GetKeyboardLayoutMap() {
 void DesktopWindowTreeHostWin::SetCursorNative(gfx::NativeCursor cursor) {
   TRACE_EVENT1("ui,input", "DesktopWindowTreeHostWin::SetCursorNative",
                "cursor", cursor.type());
+  ui::CursorLoaderWin cursor_loader;
+  cursor_loader.SetPlatformCursor(&cursor);
+
   message_handler_->SetCursor(cursor.platform());
 }