Hook Deep Scanning drag+drop on MacOS

This change was started in crrev.com/c/1814619 but is a no-op on Mac
without the changes in this CL. This only changes the drag+drop
behavior of users with the appropriate policies enabled and doesn't
affect other users.

Bug: 1046921
Change-Id: I3603ae28a730472e6f88f0281c72720c4a71be03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2037450Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Dominique Fauteux-Chapleau <domfc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738971}

content/browser/web_contents/web_contents_view_mac.mm

@@ -513,7 +513,8 @@ bool WebContentsViewMac::DraggingUpdated(DraggingInfoPtr dragging_info,
 
 bool WebContentsViewMac::PerformDragOperation(DraggingInfoPtr dragging_info,
                                               bool* out_result) {
-  *out_result = [drag_dest_ performDragOperation:dragging_info.get()];
+  *out_result = [drag_dest_ performDragOperation:dragging_info.get()
+                     withWebContentsViewDelegate:delegate_.get()];
   return true;
 }
 

content/browser/web_contents/web_drag_dest_mac.h

@@ -32,6 +32,26 @@ class DraggingInfo;
 }  // namespace remote_cocoa
 
 namespace content {
+class WebContentsViewDelegate;
+
+// A structure used to keep drop context for asynchronously finishing a drop
+// operation. This is required because some drop event data can change before
+// completeDropAsync is called.
+struct DropContext {
+  DropContext(const content::DropData drop_data,
+              const gfx::PointF client_pt,
+              const gfx::PointF screen_pt,
+              int modifier_flags,
+              base::WeakPtr<content::RenderWidgetHostImpl> target_rwh);
+  DropContext(const DropContext& other);
+  ~DropContext();
+
+  const content::DropData drop_data;
+  const gfx::PointF client_pt;
+  const gfx::PointF screen_pt;
+  const int modifier_flags;
+  base::WeakPtr<content::RenderWidgetHostImpl> target_rwh;
+};
 
 // Given |data|, which should not be nil, fill it in using the contents of the
 // given pasteboard. The types handled by this method should be kept in sync
@@ -106,7 +126,11 @@ CONTENT_EXPORT
 - (void)draggingExited;
 - (NSDragOperation)draggingUpdated:
     (const remote_cocoa::mojom::DraggingInfo*)info;
-- (BOOL)performDragOperation:(const remote_cocoa::mojom::DraggingInfo*)info;
+- (BOOL)performDragOperation:(const remote_cocoa::mojom::DraggingInfo*)info
+    withWebContentsViewDelegate:
+        (content::WebContentsViewDelegate*)webContentsViewDelegate;
+- (void)completeDropAsync:(BOOL)success
+              withContext:(const content::DropContext)context;
 
 // Helper to call WebWidgetHostInputEventRouter::GetRenderWidgetHostAtPoint().
 - (content::RenderWidgetHostImpl*)

content/browser/web_contents/web_drag_dest_mac.mm

@@ -14,6 +14,7 @@
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/common/web_contents_ns_view_bridge.mojom.h"
 #include "content/public/browser/web_contents_delegate.h"
+#include "content/public/browser/web_contents_view_delegate.h"
 #include "content/public/browser/web_drag_dest_delegate.h"
 #include "content/public/common/child_process_host.h"
 #include "content/public/common/drop_data.h"
@@ -34,6 +35,26 @@ using content::Referrer;
 using content::WebContentsImpl;
 using remote_cocoa::mojom::DraggingInfo;
 
+namespace content {
+
+DropContext::DropContext(
+    const content::DropData drop_data,
+    const gfx::PointF client_pt,
+    const gfx::PointF screen_pt,
+    int modifier_flags,
+    base::WeakPtr<content::RenderWidgetHostImpl> target_rwh)
+    : drop_data(drop_data),
+      client_pt(client_pt),
+      screen_pt(screen_pt),
+      modifier_flags(modifier_flags),
+      target_rwh(target_rwh) {}
+
+DropContext::DropContext(const DropContext& other) = default;
+
+DropContext::~DropContext() = default;
+
+}  // namespace content
+
 namespace {
 
 int GetModifierFlags() {
@@ -68,6 +89,22 @@ content::GlobalRoutingID GetRenderViewHostID(content::RenderViewHost* rvh) {
                                   rvh->GetRoutingID());
 }
 
+void DropCompletionCallback(
+    WebDragDest* drag_dest,
+    const content::DropContext context,
+    content::WebContentsViewDelegate::DropCompletionResult result) {
+  // This is an async callback. Make sure RWH is still valid.
+  if (!context.target_rwh ||
+      ![drag_dest isValidDragTarget:context.target_rwh.get()]) {
+    return;
+  }
+
+  bool success =
+      result ==
+      content::WebContentsViewDelegate::DropCompletionResult::kContinue;
+  [drag_dest completeDropAsync:success withContext:context];
+}
+
 }  // namespace
 
 @implementation WebDragDest
@@ -280,7 +317,9 @@ content::GlobalRoutingID GetRenderViewHostID(content::RenderViewHost* rvh) {
   return _currentOperation;
 }
 
-- (BOOL)performDragOperation:(const DraggingInfo*)info {
+- (BOOL)performDragOperation:(const DraggingInfo*)info
+    withWebContentsViewDelegate:
+        (content::WebContentsViewDelegate*)webContentsViewDelegate {
   gfx::PointF transformedPt;
   content::RenderWidgetHostImpl* targetRWH =
       [self GetRenderWidgetHostAtPoint:info->location_in_view
@@ -308,21 +347,46 @@ content::GlobalRoutingID GetRenderViewHostID(content::RenderViewHost* rvh) {
     }
   }
 
-  if (_delegate)
-    _delegate->OnDrop();
-
   _currentRVH = NULL;
-
   _webContents->Focus();
-  targetRWH->DragTargetDrop(*_dropDataFiltered, transformedPt,
-                            info->location_in_screen, GetModifierFlags());
 
+  if (webContentsViewDelegate) {
+    content::DropContext context(/*drop_data=*/*_dropDataFiltered,
+                                 /*client_pt=*/transformedPt,
+                                 /*screen_pt=*/info->location_in_screen,
+                                 /*modifier_flags=*/GetModifierFlags(),
+                                 /*target_rwh=*/targetRWH->GetWeakPtr());
+
+    webContentsViewDelegate->OnPerformDrop(
+        context.drop_data,
+        base::BindOnce(&DropCompletionCallback, self, context));
+  } else {
+    if (_delegate)
+      _delegate->OnDrop();
+    targetRWH->DragTargetDrop(*_dropDataFiltered, transformedPt,
+                              info->location_in_screen, GetModifierFlags());
+  }
   _dropDataUnfiltered.reset();
   _dropDataFiltered.reset();
 
   return YES;
 }
 
+- (void)completeDropAsync:(BOOL)success
+              withContext:(const content::DropContext)context {
+  if (success) {
+    if (_delegate)
+      _delegate->OnDrop();
+    context.target_rwh->DragTargetDrop(context.drop_data, context.client_pt,
+                                       context.screen_pt,
+                                       context.modifier_flags);
+  } else {
+    if (_delegate)
+      _delegate->OnDragLeave();
+    context.target_rwh->DragTargetDragLeave(gfx::PointF(), gfx::PointF());
+  }
+}
+
 - (content::RenderWidgetHostImpl*)
     GetRenderWidgetHostAtPoint:(const gfx::PointF&)viewPoint
                  transformedPt:(gfx::PointF*)transformedPt {