Bug 1586471 - Part 3. Allow to drop data from external application on GeckoView. r=dom-core,geckoview-reviewers,amejiamarmol,edgar

The dropped item is set on drop event handler in Android. Current
Gecko's implementation caches dropped item as `DataTransfer` when any
drag events are fired. It will works on desktop platform, but doesn't
on GeckoView. Even if drop item is set by handling drop event,
`DataTransfer`'s cache isn't refreshed.

So if drop event is received, we re-fill DataTransfer on GeckoView.

Differential Revision: https://phabricator.services.mozilla.com/D197331

dom/events/EventStateManager.cpp

@@ -1720,7 +1720,8 @@ void EventStateManager::DispatchCrossProcessEvent(WidgetEvent* aEvent,
     }
     case eDragEventClass: {
       RefPtr<BrowserParent> browserParent = remote;
-      browserParent->Manager()->MaybeInvokeDragSession(browserParent);
+      browserParent->Manager()->MaybeInvokeDragSession(browserParent,
+                                                       aEvent->mMessage);
 
       nsCOMPtr<nsIDragSession> dragSession = nsContentUtils::GetDragSession();
       uint32_t dropEffect = nsIDragService::DRAGDROP_ACTION_NONE;

dom/ipc/ContentChild.cpp

@@ -3152,13 +3152,53 @@ mozilla::ipc::IPCResult ContentChild::RecvPWebBrowserPersistDocumentConstructor(
   return IPC_OK();
 }
 
+static already_AddRefed<DataTransfer> ConvertToDataTransfer(
+    nsTArray<IPCTransferableData>&& aTransferables, EventMessage aMessage) {
+  // Check if we are receiving any file objects. If we are we will want
+  // to hide any of the other objects coming in from content.
+  bool hasFiles = false;
+  for (uint32_t i = 0; i < aTransferables.Length() && !hasFiles; ++i) {
+    auto& items = aTransferables[i].items();
+    for (uint32_t j = 0; j < items.Length() && !hasFiles; ++j) {
+      if (items[j].data().type() ==
+          IPCTransferableDataType::TIPCTransferableDataBlob) {
+        hasFiles = true;
+      }
+    }
+  }
+  // Add the entries from the IPC to the new DataTransfer
+  RefPtr<DataTransfer> dataTransfer =
+      new DataTransfer(nullptr, aMessage, false, -1);
+  for (uint32_t i = 0; i < aTransferables.Length(); ++i) {
+    auto& items = aTransferables[i].items();
+    for (uint32_t j = 0; j < items.Length(); ++j) {
+      const IPCTransferableDataItem& item = items[j];
+      RefPtr<nsVariantCC> variant = new nsVariantCC();
+      nsresult rv =
+          nsContentUtils::IPCTransferableDataItemToVariant(item, variant);
+      if (NS_FAILED(rv)) {
+        continue;
+      }
+
+      // We should hide this data from content if we have a file, and we
+      // aren't a file.
+      bool hidden =
+          hasFiles && item.data().type() !=
+                          IPCTransferableDataType::TIPCTransferableDataBlob;
+      dataTransfer->SetDataWithPrincipalFromOtherProcess(
+          NS_ConvertUTF8toUTF16(item.flavor()), variant, i,
+          nsContentUtils::GetSystemPrincipal(), hidden);
+    }
+  }
+  return dataTransfer.forget();
+}
+
 mozilla::ipc::IPCResult ContentChild::RecvInvokeDragSession(
     const MaybeDiscarded<WindowContext>& aSourceWindowContext,
     const MaybeDiscarded<WindowContext>& aSourceTopWindowContext,
     nsTArray<IPCTransferableData>&& aTransferables, const uint32_t& aAction) {
-  nsCOMPtr<nsIDragService> dragService =
-      do_GetService("@mozilla.org/widget/dragservice;1");
-  if (dragService) {
+  if (nsCOMPtr<nsIDragService> dragService =
+          do_GetService("@mozilla.org/widget/dragservice;1")) {
     dragService->StartDragSession();
     nsCOMPtr<nsIDragSession> session;
     dragService->GetCurrentSession(getter_AddRefs(session));
@@ -3167,43 +3207,25 @@ mozilla::ipc::IPCResult ContentChild::RecvInvokeDragSession(
       session->SetSourceTopWindowContext(
           aSourceTopWindowContext.GetMaybeDiscarded());
       session->SetDragAction(aAction);
-      // Check if we are receiving any file objects. If we are we will want
-      // to hide any of the other objects coming in from content.
-      bool hasFiles = false;
-      for (uint32_t i = 0; i < aTransferables.Length() && !hasFiles; ++i) {
-        auto& items = aTransferables[i].items();
-        for (uint32_t j = 0; j < items.Length() && !hasFiles; ++j) {
-          if (items[j].data().type() ==
-              IPCTransferableDataType::TIPCTransferableDataBlob) {
-            hasFiles = true;
-          }
-        }
-      }
 
-      // Add the entries from the IPC to the new DataTransfer
+      RefPtr<DataTransfer> dataTransfer =
+          ConvertToDataTransfer(std::move(aTransferables), eDragStart);
+      session->SetDataTransfer(dataTransfer);
+    }
+  }
+  return IPC_OK();
+}
+
+mozilla::ipc::IPCResult ContentChild::RecvUpdateDragSession(
+    nsTArray<IPCTransferableData>&& aTransferables,
+    EventMessage aEventMessage) {
+  if (nsCOMPtr<nsIDragService> dragService =
+          do_GetService("@mozilla.org/widget/dragservice;1")) {
+    nsCOMPtr<nsIDragSession> session;
+    dragService->GetCurrentSession(getter_AddRefs(session));
+    if (session) {
       nsCOMPtr<DataTransfer> dataTransfer =
-          new DataTransfer(nullptr, eDragStart, false, -1);
-      for (uint32_t i = 0; i < aTransferables.Length(); ++i) {
-        auto& items = aTransferables[i].items();
-        for (uint32_t j = 0; j < items.Length(); ++j) {
-          const IPCTransferableDataItem& item = items[j];
-          RefPtr<nsVariantCC> variant = new nsVariantCC();
-          nsresult rv =
-              nsContentUtils::IPCTransferableDataItemToVariant(item, variant);
-          if (NS_FAILED(rv)) {
-            continue;
-          }
-
-          // We should hide this data from content if we have a file, and we
-          // aren't a file.
-          bool hidden =
-              hasFiles && item.data().type() !=
-                              IPCTransferableDataType::TIPCTransferableDataBlob;
-          dataTransfer->SetDataWithPrincipalFromOtherProcess(
-              NS_ConvertUTF8toUTF16(item.flavor()), variant, i,
-              nsContentUtils::GetSystemPrincipal(), hidden);
-        }
-      }
+          ConvertToDataTransfer(std::move(aTransferables), aEventMessage);
       session->SetDataTransfer(dataTransfer);
     }
   }

dom/ipc/ContentChild.h

@@ -415,6 +415,10 @@ class ContentChild final : public PContentChild,
       const MaybeDiscarded<WindowContext>& aSourceTopWindowContext,
       nsTArray<IPCTransferableData>&& aTransferables, const uint32_t& aAction);
 
+  mozilla::ipc::IPCResult RecvUpdateDragSession(
+      nsTArray<IPCTransferableData>&& aTransferables,
+      EventMessage aEventMessage);
+
   MOZ_CAN_RUN_SCRIPT_BOUNDARY
   mozilla::ipc::IPCResult RecvEndDragSession(
       const bool& aDoneDrag, const bool& aUserCancelled,

dom/ipc/ContentParent.cpp

@@ -5358,7 +5358,28 @@ bool ContentParent::DeallocPWebrtcGlobalParent(PWebrtcGlobalParent* aActor) {
 }
 #endif
 
-void ContentParent::MaybeInvokeDragSession(BrowserParent* aParent) {
+void ContentParent::GetIPCTransferableData(
+    nsIDragSession* aSession, BrowserParent* aParent,
+    nsTArray<IPCTransferableData>& aIPCTransferables) {
+  RefPtr<DataTransfer> transfer = aSession->GetDataTransfer();
+  if (!transfer) {
+    // Pass eDrop to get DataTransfer with external
+    // drag formats cached.
+    transfer = new DataTransfer(nullptr, eDrop, true, -1);
+    aSession->SetDataTransfer(transfer);
+  }
+  // Note, even though this fills the DataTransfer object with
+  // external data, the data is usually transfered over IPC lazily when
+  // needed.
+  transfer->FillAllExternalData();
+  nsCOMPtr<nsILoadContext> lc = aParent ? aParent->GetLoadContext() : nullptr;
+  nsCOMPtr<nsIArray> transferables = transfer->GetTransferables(lc);
+  nsContentUtils::TransferablesToIPCTransferableDatas(
+      transferables, aIPCTransferables, false, this);
+}
+
+void ContentParent::MaybeInvokeDragSession(BrowserParent* aParent,
+                                           EventMessage aMessage) {
   // dnd uses IPCBlob to transfer data to the content process and the IPC
   // message is sent as normal priority. When sending input events with input
   // priority, the message may be preempted by the later dnd events. To make
@@ -5369,28 +5390,17 @@ void ContentParent::MaybeInvokeDragSession(BrowserParent* aParent) {
 
   nsCOMPtr<nsIDragService> dragService =
       do_GetService("@mozilla.org/widget/dragservice;1");
-  if (dragService && dragService->MaybeAddChildProcess(this)) {
-    // We need to send transferable data to child process.
+  if (!dragService) {
+    return;
+  }
+
+  if (dragService->MaybeAddChildProcess(this)) {
     nsCOMPtr<nsIDragSession> session;
     dragService->GetCurrentSession(getter_AddRefs(session));
     if (session) {
+      // We need to send transferable data to child process.
       nsTArray<IPCTransferableData> ipcTransferables;
-      RefPtr<DataTransfer> transfer = session->GetDataTransfer();
-      if (!transfer) {
-        // Pass eDrop to get DataTransfer with external
-        // drag formats cached.
-        transfer = new DataTransfer(nullptr, eDrop, true, -1);
-        session->SetDataTransfer(transfer);
-      }
-      // Note, even though this fills the DataTransfer object with
-      // external data, the data is usually transfered over IPC lazily when
-      // needed.
-      transfer->FillAllExternalData();
-      nsCOMPtr<nsILoadContext> lc =
-          aParent ? aParent->GetLoadContext() : nullptr;
-      nsCOMPtr<nsIArray> transferables = transfer->GetTransferables(lc);
-      nsContentUtils::TransferablesToIPCTransferableDatas(
-          transferables, ipcTransferables, false, this);
+      GetIPCTransferableData(session, aParent, ipcTransferables);
       uint32_t action;
       session->GetDragAction(&action);
 
@@ -5401,6 +5411,19 @@ void ContentParent::MaybeInvokeDragSession(BrowserParent* aParent) {
       mozilla::Unused << SendInvokeDragSession(
           sourceWC, sourceTopWC, std::move(ipcTransferables), action);
     }
+    return;
+  }
+
+  if (dragService->MustUpdateDataTransfer(aMessage)) {
+    nsCOMPtr<nsIDragSession> session;
+    dragService->GetCurrentSession(getter_AddRefs(session));
+    if (session) {
+      // We need to send transferable data to child process.
+      nsTArray<IPCTransferableData> ipcTransferables;
+      GetIPCTransferableData(session, aParent, ipcTransferables);
+      mozilla::Unused << SendUpdateDragSession(std::move(ipcTransferables),
+                                               aMessage);
+    }
   }
 }
 

dom/ipc/ContentParent.h

@@ -463,7 +463,7 @@ class ContentParent final : public PContentParent,
 
   mozilla::ipc::IPCResult RecvNotifyShutdownSuccess();
 
-  void MaybeInvokeDragSession(BrowserParent* aParent);
+  void MaybeInvokeDragSession(BrowserParent* aParent, EventMessage aMessage);
 
   PContentPermissionRequestParent* AllocPContentPermissionRequestParent(
       const nsTArray<PermissionRequest>& aRequests, nsIPrincipal* aPrincipal,
@@ -1417,6 +1417,9 @@ class ContentParent final : public PContentParent,
     return mThreadsafeHandle;
   }
 
+  void GetIPCTransferableData(nsIDragSession* aSession, BrowserParent* aParent,
+                              nsTArray<IPCTransferableData>& aIPCTransferables);
+
  private:
   // Return an existing ContentParent if possible. Otherwise, `nullptr`.
   static already_AddRefed<ContentParent> GetUsedBrowserProcess(

dom/ipc/PContent.ipdl

@@ -98,6 +98,7 @@ using mozilla::gfx::IntSize from "mozilla/gfx/2D.h";
 using mozilla::gfx::SurfaceFormat from "mozilla/gfx/Types.h";
 using mozilla::dom::TabId from "mozilla/dom/ipc/IdType.h";
 using mozilla::dom::ContentParentId from "mozilla/dom/ipc/IdType.h";
+using mozilla::EventMessage from "mozilla/EventForwards.h";
 using mozilla::LayoutDeviceIntPoint from "Units.h";
 using mozilla::ImagePoint from "Units.h";
 using mozilla::ImageIntSize from "Units.h";
@@ -824,6 +825,8 @@ child:
                             MaybeDiscardedWindowContext aSourceTopWindowContext,
                             IPCTransferableData[] transfers, uint32_t action);
 
+    async UpdateDragSession(IPCTransferableData[] transfers, EventMessage message);
+
     async EndDragSession(bool aDoneDrag, bool aUserCancelled,
                          LayoutDeviceIntPoint aDragEndPoint,
                          uint32_t aKeyModifiers,

widget/android/nsDragService.cpp

@@ -186,6 +186,12 @@ nsDragService::UpdateDragImage(nsINode* aImage, int32_t aImageX,
   return NS_OK;
 }
 
+bool nsDragService::MustUpdateDataTransfer(EventMessage aMessage) {
+  // Android's drag and drop API sets drop item in drop event.
+  // So we have to invalidate data transfer cache on drop event.
+  return aMessage == eDrop;
+}
+
 java::sdk::Bitmap::LocalRef nsDragService::CreateDragImage(
     nsINode* aNode, const Maybe<CSSIntRegion>& aRegion) {
   LayoutDeviceIntRect dragRect;
@@ -218,6 +224,8 @@ java::sdk::Bitmap::LocalRef nsDragService::CreateDragImage(
 
 void nsDragService::SetData(nsITransferable* aTransferable) {
   mTransferable = aTransferable;
+  // Reset DataTransfer
+  mDataTransfer = nullptr;
 }
 
 // static

widget/android/nsDragService.h

@@ -30,6 +30,7 @@ class nsDragService final : public nsBaseDragService {
                                                uint32_t aKeyModifiers) override;
   NS_IMETHOD
   UpdateDragImage(nsINode* aImage, int32_t aImageX, int32_t aImageY) override;
+  virtual bool MustUpdateDataTransfer(mozilla::EventMessage aMessage) override;
 
   void SetData(nsITransferable* aTransferable);
 

widget/nsBaseDragService.cpp

@@ -1025,6 +1025,10 @@ bool nsBaseDragService::RemoveAllChildProcesses() {
   return true;
 }
 
+bool nsBaseDragService::MustUpdateDataTransfer(EventMessage aMessage) {
+  return false;
+}
+
 NS_IMETHODIMP
 nsBaseDragService::MaybeEditorDeletedSourceNode(Element* aEditingHost) {
   // If builtin editor of Blink and WebKit deletes the source node,they retarget

widget/nsIDragService.idl

@@ -194,6 +194,11 @@ interface nsIDragService : nsISupports
   [notxpcom, nostdcall] boolean maybeAddChildProcess(in ContentParentPtr aChild);
   [notxpcom, nostdcall] boolean removeAllChildProcesses();
 
+  /**
+   * Retrun true if nsIDragSession's data is updated.
+   */
+  [notxpcom, nostdcall] boolean mustUpdateDataTransfer(in EventMessage aMessage);
+
   /**
    * Called when HTMLEditor maybe deleted the source node from the document.
    *