Move handling of DraggableRegionsChanged notification from "view" to "frame".

extensions/renderer/extension_frame_helper.cc

Index: extensions/renderer/extension_frame_helper.cc
diff --git a/extensions/renderer/extension_frame_helper.cc b/extensions/renderer/extension_frame_helper.cc
index da47e687f5662c0d8eefb6830a860edf971c2689..093b17b10cea5859167ae441c43fc10491b93f3e 100644
--- a/extensions/renderer/extension_frame_helper.cc
+++ b/extensions/renderer/extension_frame_helper.cc
@@ -8,6 +8,7 @@
 #include "base/strings/string_util.h"
 #include "base/timer/elapsed_timer.h"
 #include "content/public/renderer/render_frame.h"
+#include "content/public/renderer/render_view.h"
 #include "extensions/common/api/messaging/message.h"
 #include "extensions/common/api/messaging/port_id.h"
 #include "extensions/common/constants.h"
@@ -335,4 +336,22 @@ void ExtensionFrameHelper::OnDestruct() {
   delete this;
 }
 
+void ExtensionFrameHelper::DraggableRegionsChanged() {
+  if (!render_frame()->IsMainFrame())
+    return;
+
+  blink::WebVector<blink::WebDraggableRegion> webregions =
+      render_frame()->GetWebFrame()->GetDocument().DraggableRegions();
+  std::vector<DraggableRegion> regions;
+  for (size_t i = 0; i < webregions.size(); ++i) {

[Devlin, 2017/06/13 18:38:30]

update this to const blink::WebDraggableRegion&

[Łukasz Anforowicz, 2017/06/13 20:48:42]

Done, good point.  (non-const ref, because ConvertViewport... needs to mutate
vector elements;  I've considered using const-ref and then mutating a local
blink::WebRect, but that would involve copying it later which would run counter
to your other comment).

+    DraggableRegion region;

[Devlin, 2017/06/13 18:38:30]

A minor optimization here would be something like:
regions.push_back(DraggableRegion());
DraggableRegion& region = regions.back();

That way we avoid the copy/assignment.

Option 2 would be adding move semantics to DraggableRegion, which would also be
okay.

[Łukasz Anforowicz, 2017/06/13 20:48:42]

Done, although I am not sure if this matters much.  I've done option #1.  It
seems that DraggableRegion is a struct of PODs (bool + 4 ints [nested in
gfx::Rect/Size/Point]) and therefore should be automatically movable (i.e. the
default move constructor/assignment should be reasonable;  or in other words -
it is hard to see how a move [discarding the old value] could be more efficient
than a copy).

+    render_frame()->GetRenderView()->ConvertViewportToWindowViaWidget(
+        &webregions[i].bounds);
+    region.bounds = webregions[i].bounds;
+    region.draggable = webregions[i].draggable;
+    regions.push_back(region);
+  }
+  Send(new ExtensionHostMsg_UpdateDraggableRegions(routing_id(), regions));
+}
+
 }  // namespace extensions