Correctly set dragLeave and dragEnd coords for OOPIF drag and drop

content/browser/web_contents/web_drag_source_mac.mm

Index: content/browser/web_contents/web_drag_source_mac.mm
diff --git a/content/browser/web_contents/web_drag_source_mac.mm b/content/browser/web_contents/web_drag_source_mac.mm
index fdd46497ad47345bd0149631a2155878443973fc..ad2a9d658f6375fd831f73ca0a9387bbe78171b8 100644
--- a/content/browser/web_contents/web_drag_source_mac.mm
+++ b/content/browser/web_contents/web_drag_source_mac.mm
@@ -23,6 +23,7 @@
 #include "content/browser/download/drag_download_util.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/browser/renderer_host/render_widget_host_impl.h"
+#include "content/browser/renderer_host/render_widget_host_view_base.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/content_browser_client.h"
 #include "content/public/common/content_client.h"
@@ -291,12 +292,28 @@ void PromiseWriterHelper(const DropData& drop_data,
   if (operation == (NSDragOperationMove | NSDragOperationCopy))
     operation &= ~NSDragOperationMove;
 
-  // TODO(paulmeyer):  In the OOPIF case, should |localPoint| be converted to
-  // the coordinates local to |dragStartRWH_|?
+  // |localPoint| and |screenPoint| are in the root coordinate space, for
+  // non-root RenderWidgetHosts they need to be transformed.
+  gfx::Point transformedPoint = gfx::Point(localPoint.x, localPoint.y);
+  gfx::Point transformedScreenPoint = gfx::Point(screenPoint.x, screenPoint.y);
+  static_cast<content::RenderWidgetHostViewBase*>(
+      contents_->GetRenderWidgetHostView())
+      ->TransformPointToCoordSpaceForView(
+          gfx::Point(localPoint.x, localPoint.y),
+          static_cast<content::RenderWidgetHostViewBase*>(
+              dragStartRWH_->GetView()),
+          &transformedPoint);
+  static_cast<content::RenderWidgetHostViewBase*>(
+      contents_->GetRenderWidgetHostView())
+      ->TransformPointToCoordSpaceForView(
+          gfx::Point(screenPoint.x, screenPoint.y),
+          static_cast<content::RenderWidgetHostViewBase*>(
+              dragStartRWH_->GetView()),
+          &transformedScreenPoint);

[dcheng, 2017/02/01 20:45:31]

Is it possible to have more of these utility functions shared in general? For
example, lines 279 - 287 seem pretty similar to flipWindowPointToView /
flipWindowPointToScreen in web_drag_dest_mac.mm, and then we have similar
transformations in the rest of the drag/drop code as well.

In addition, I find this block of code a bit difficult to read... there's a lot
of downcasting involved.

[kenrb, 2017/02/02 21:21:03]

I have made changes to make the point transformation calls more readable.

As for the the coordinate flipping, is there something specific you had in mind?
There isn't a convenient Mac utility file under content/browser/web_contents
that I can see, and it is a stretch to create one for such a small change. I am
reluctant to undertake a larger refactor in part because I am a novice with
Objective-C++, and in part because I don't want to block this bug fix on
something like that.

   contents_->DragSourceEndedAt(
-      localPoint.x, localPoint.y, screenPoint.x, screenPoint.y,
-      static_cast<blink::WebDragOperation>(operation),
-      dragStartRWH_.get());
+      transformedPoint.x(), transformedPoint.y(), transformedScreenPoint.x(),
+      transformedScreenPoint.y(),
+      static_cast<blink::WebDragOperation>(operation), dragStartRWH_.get());
 
   // Make sure the pasteboard owner isn't us.
   [pasteboard_ declareTypes:[NSArray array] owner:nil];