Merge Window into FlutterWindow (#45542)

Merge abstract base class `Window` into concrete derived class
`FlutterWindow` to simplify future development.

flutter/flutter#132260

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above.
- [x] I added new tests to check the change I am making or feature I am
adding, or the PR is [test-exempt]. See [testing the engine] for
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---------

Co-authored-by: Loïc Sharma <[email protected]>

Author: yaakovschectman

ci/licenses_golden/licenses_flutter

@@ -3288,8 +3288,6 @@ ORIGIN: ../../../flutter/shell/platform/windows/text_input_manager.h + ../../../
 ORIGIN: ../../../flutter/shell/platform/windows/text_input_plugin.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/text_input_plugin.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/text_input_plugin_delegate.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/shell/platform/windows/window.cc + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/shell/platform/windows/window.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/window_binding_handler.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.cc + ../../../flutter/LICENSE
@@ -6060,8 +6058,6 @@ FILE: ../../../flutter/shell/platform/windows/text_input_manager.h
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.h
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin_delegate.h
-FILE: ../../../flutter/shell/platform/windows/window.cc
-FILE: ../../../flutter/shell/platform/windows/window.h
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler.h
 FILE: ../../../flutter/shell/platform/windows/window_binding_handler_delegate.h
 FILE: ../../../flutter/shell/platform/windows/window_proc_delegate_manager.cc

shell/platform/windows/BUILD.gn

@@ -96,8 +96,6 @@ source_set("flutter_windows_source") {
     "text_input_manager.h",
     "text_input_plugin.cc",
     "text_input_plugin.h",
-    "window.cc",
-    "window.h",
     "window_binding_handler.h",
     "window_binding_handler_delegate.h",
     "window_proc_delegate_manager.cc",

shell/platform/windows/direct_manipulation.cc

@@ -7,7 +7,7 @@
 #include <algorithm>
 
 #include "flutter/shell/platform/windows/direct_manipulation.h"
-#include "flutter/shell/platform/windows/window.h"
+#include "flutter/shell/platform/windows/flutter_window.h"
 #include "flutter/shell/platform/windows/window_binding_handler_delegate.h"
 
 #define RETURN_IF_FAILED(operation)            \
@@ -172,7 +172,7 @@ ULONG STDMETHODCALLTYPE DirectManipulationEventHandler::Release() {
   return 0;
 }
 
-DirectManipulationOwner::DirectManipulationOwner(Window* window)
+DirectManipulationOwner::DirectManipulationOwner(FlutterWindow* window)
     : window_(window) {}
 
 int DirectManipulationOwner::Init(unsigned int width, unsigned int height) {

shell/platform/windows/direct_manipulation.h

@@ -12,7 +12,7 @@
 
 namespace flutter {
 
-class Window;
+class FlutterWindow;
 class WindowBindingHandlerDelegate;
 
 class DirectManipulationEventHandler;
@@ -21,7 +21,7 @@ class DirectManipulationEventHandler;
 // DirectManipulation and WindowBindingHandlerDelegate.
 class DirectManipulationOwner {
  public:
-  explicit DirectManipulationOwner(Window* window);
+  explicit DirectManipulationOwner(FlutterWindow* window);
   virtual ~DirectManipulationOwner() = default;
   // Initialize a DirectManipulation viewport with specified width and height.
   // These should match the width and height of the application window.
@@ -47,7 +47,7 @@ class DirectManipulationOwner {
 
  private:
   // The window gesture input is occuring on.
-  Window* window_;
+  FlutterWindow* window_;
   // Cookie needed to register child event handler with viewport.
   DWORD viewportHandlerCookie_;
   // Object needed for operation of the DirectManipulation API.