Direct HWND fetching for Windows navigator.Share

Updating how the Windows implementation of navigator.Share attempts to
fetch the HWND designated for accessibility with the WebContents. This
change allows it to successfully fetch said HWND, even if not all the
accessibility components have been initialized yet (which may happen if
no accessibility tools have been detected).

Bug: 1413618
Change-Id: Ia0ded852ea0c966ac35342c3cd23bf445ebf8305
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4245222
Commit-Queue: Daniel Murphy <dmurph@chromium.org>
Auto-Submit: Hoch Hochkeppel <mhochk@microsoft.com>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1104616}

chrome/browser/webshare/win/share_operation.cc

@@ -15,16 +15,14 @@
 #include "chrome/browser/webshare/win/show_share_ui_for_window_operation.h"
 #include "content/public/browser/browser_task_traits.h"
 #include "content/public/browser/browser_thread.h"
-#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "net/base/net_errors.h"
 #include "storage/browser/blob/blob_data_handle.h"
 #include "storage/browser/blob/blob_storage_context.h"
 #include "storage/browser/file_system/file_stream_writer.h"
 #include "storage/browser/file_system/file_writer_delegate.h"
 #include "storage/common/file_system/file_system_mount_option.h"
-#include "ui/accessibility/platform/ax_platform_node.h"
-#include "ui/accessibility/platform/ax_platform_node_delegate.h"
+#include "ui/base/win/internal_constants.h"
 #include "ui/views/win/hwnd_util.h"
 #include "url/gurl.h"
 
@@ -427,32 +425,29 @@ void ShareOperation::Run(blink::mojom::ShareService::ShareCallback callback) {
     }
   }
 
-  // Attempt to fetch the accessibility HWND for these WebContents. For the
-  // sake of better communication with screen readers this HWND is (virtually)
-  // scoped to just the WebContents (rather than the entire actual window), so
-  // allows the resulting Share dialog to also better position/associate itself
-  // with the WebContents.
-  HWND hwnd = nullptr;
-  content::RenderWidgetHostView* host_view =
-      web_contents_->GetTopLevelRenderWidgetHostView();
-  if (host_view) {
-    ui::AXPlatformNode* platform_node =
-        ui::AXPlatformNode::FromNativeViewAccessible(
-            host_view->GetNativeViewAccessible());
-    if (platform_node) {
-      ui::AXPlatformNodeDelegate* delegate = platform_node->GetDelegate();
-      if (delegate) {
-        hwnd = delegate->GetTargetForNativeAccessibilityEvent();
-      }
+  HWND hwnd =
+      views::HWNDForNativeWindow(web_contents_->GetTopLevelNativeWindow());
+
+  // Attempt to fetch the special HWND maintained for the primary WebContents of
+  // this window. For the sake of better communication with screen readers this
+  // HWND is (virtually) scoped to the same space as the WebContents (rather
+  // than the entire actual window), so allows the resulting Share dialog to
+  // better position/associate itself with the WebContents.
+  //
+  // Note: Though this is exposed to accessibility tools via standardized routes
+  // we could expect to leverage here, the browser may choose to not set up all
+  // these routes until an accessibility tool has been detected. Instead we look
+  // for this specific class directly so we can find it even if accessibility
+  // has not been configured yet.
+  if (hwnd) {
+    HWND accessible_hwnd =
+        ::FindWindowExW(/*hWndParent*/ hwnd, /*hWndChildAfter*/ NULL,
+                        /*lpszClass*/ ui::kLegacyRenderWidgetHostHwnd,
+                        /*lpszWindow*/ NULL);
+    if (accessible_hwnd) {
+      hwnd = accessible_hwnd;
     }
   }
-  // If we were unable to fetch the accessibility HWND, fall-back to the
-  // top-level HWND, which will still function appropriately, it just may not
-  // position as nicely. This is unexpected in most cases, but can happen if,
-  // for example, Windows has explicitly destroyed said HWND.
-  if (!hwnd) {
-    hwnd = views::HWNDForNativeWindow(web_contents_->GetTopLevelNativeWindow());
-  }
 
   show_share_ui_for_window_operation_ =
       std::make_unique<ShowShareUIForWindowOperation>(hwnd);