Add support for draggable regions (issue #1645).

Regions are defined using the '-webkit-app-region: drag/no-drag'
CSS property and passed to the CefDragHandler::
OnDraggableRegionsChanged callback.

libcef/browser/browser_host_impl.cc

@@ -2659,6 +2659,8 @@ bool CefBrowserHostImpl::OnMessageReceived(const IPC::Message& message) {
   IPC_BEGIN_MESSAGE_MAP(CefBrowserHostImpl, message)
     IPC_MESSAGE_HANDLER(CefHostMsg_FrameIdentified, OnFrameIdentified)
     IPC_MESSAGE_HANDLER(CefHostMsg_DidFinishLoad, OnDidFinishLoad)
+    IPC_MESSAGE_HANDLER(CefHostMsg_UpdateDraggableRegions,
+                        OnUpdateDraggableRegions)
     IPC_MESSAGE_HANDLER(CefHostMsg_Request, OnRequest)
     IPC_MESSAGE_HANDLER(CefHostMsg_Response, OnResponse)
     IPC_MESSAGE_HANDLER(CefHostMsg_ResponseAck, OnResponseAck)
@@ -2716,6 +2718,26 @@ void CefBrowserHostImpl::OnDidFinishLoad(int64 frame_id,
   OnLoadEnd(frame, validated_url, http_status_code);
 }
 
+void CefBrowserHostImpl::OnUpdateDraggableRegions(
+    const std::vector<Cef_DraggableRegion_Params>& regions) {
+  std::vector<CefDraggableRegion> draggable_regions;
+  draggable_regions.reserve(regions.size());
+
+  std::vector<Cef_DraggableRegion_Params>::const_iterator it = regions.begin();
+  for (; it != regions.end(); ++it) {
+    const gfx::Rect& rect(it->bounds);
+    const CefRect bounds(rect.x(), rect.y(), rect.width(), rect.height());
+    draggable_regions.push_back(CefDraggableRegion(bounds, it->draggable));
+  }
+
+  if (client_.get()) {
+    CefRefPtr<CefDragHandler> handler = client_->GetDragHandler();
+    if (handler.get()) {
+      handler->OnDraggableRegionsChanged(this, draggable_regions);
+    }
+  }
+}
+
 void CefBrowserHostImpl::OnRequest(const Cef_Request_Params& params) {
   bool success = false;
   std::string response;

libcef/browser/browser_host_impl.h

@@ -64,6 +64,7 @@ class Widget;
 class CefWindowX11;
 #endif
 
+struct Cef_DraggableRegion_Params;
 struct Cef_Request_Params;
 struct Cef_Response_Params;
 class CefBrowserInfo;
@@ -477,6 +478,8 @@ class CefBrowserHostImpl : public CefBrowserHost,
       const GURL& validated_url,
       bool is_main_frame,
       int http_status_code);
+  void OnUpdateDraggableRegions(
+      const std::vector<Cef_DraggableRegion_Params>& regions);
   void OnRequest(const Cef_Request_Params& params);
   void OnResponse(const Cef_Response_Params& params);
   void OnResponseAck(int request_id);

libcef/common/cef_messages.h

@@ -68,6 +68,12 @@ IPC_STRUCT_BEGIN(Cef_CrossOriginWhiteListEntry_Params)
   IPC_STRUCT_MEMBER(bool, allow_target_subdomains)
 IPC_STRUCT_END()
 
+// Parameters structure for a draggable region.
+IPC_STRUCT_BEGIN(Cef_DraggableRegion_Params)
+  IPC_STRUCT_MEMBER(gfx::Rect, bounds)
+  IPC_STRUCT_MEMBER(bool, draggable)
+IPC_STRUCT_END()
+
 
 // Messages sent from the browser to the renderer.
 
@@ -189,6 +195,10 @@ IPC_MESSAGE_ROUTED1(CefHostMsg_Response,
 IPC_MESSAGE_ROUTED1(CefHostMsg_ResponseAck,
                     int /* request_id */)
 
+// Sent by the renderer when the draggable regions are updated.
+IPC_MESSAGE_ROUTED1(CefHostMsg_UpdateDraggableRegions,
+                    std::vector<Cef_DraggableRegion_Params> /* regions */)
+
 
 // Singly-included section for struct and custom IPC traits.
 #ifndef CEF_LIBCEF_COMMON_CEF_MESSAGES_H_

libcef/renderer/browser_impl.cc

@@ -571,6 +571,19 @@ void CefBrowserImpl::FocusedNodeChanged(const blink::WebNode& node) {
   }
 }
 
+void CefBrowserImpl::DraggableRegionsChanged(blink::WebFrame* frame) {
+  blink::WebVector<blink::WebDraggableRegion> webregions =
+      frame->document().draggableRegions();
+  std::vector<Cef_DraggableRegion_Params> regions;
+  for (size_t i = 0; i < webregions.size(); ++i) {
+    Cef_DraggableRegion_Params region;
+    region.bounds = webregions[i].bounds;
+    region.draggable = webregions[i].draggable;
+    regions.push_back(region);
+  }
+  Send(new CefHostMsg_UpdateDraggableRegions(routing_id(), regions));
+}
+
 bool CefBrowserImpl::OnMessageReceived(const IPC::Message& message) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP(CefBrowserImpl, message)

libcef/renderer/browser_impl.h

@@ -119,6 +119,7 @@ class CefBrowserImpl : public CefBrowser,
                                 bool is_new_navigation) override;
   void FrameDetached(blink::WebFrame* frame) override;
   void FocusedNodeChanged(const blink::WebNode& node) override;
+  void DraggableRegionsChanged(blink::WebFrame* frame) override;
   bool OnMessageReceived(const IPC::Message& message) override;
 
   // RenderViewObserver::OnMessageReceived message handlers.