Keep list of bridgeIds associated with each ViewBackend

As each ViewBackend (and hence web view) can get its contents rendered
by different WPEWebProcess due to PSON, keep around a list of all the
differen bridgeIds which have been associated with it in a std::vector.
Newly added elements are always pushed at the back, so the most recent
association (i.e. the "current" active one) is always the last element.
Keeping the list allows getting back to the previously used ones.

(cherry picked from commit 3af2f17)

src/view-backend-private.cpp

@@ -28,6 +28,7 @@
 #include <cassert>
 #include <sys/types.h>
 #include <sys/socket.h>
+#include <algorithm>
 
 ViewBackend::ViewBackend(ClientBundle* clientBundle, struct wpe_view_backend* backend)
     : m_clientBundle(clientBundle)
@@ -38,7 +39,8 @@ ViewBackend::ViewBackend(ClientBundle* clientBundle, struct wpe_view_backend* ba
 
 ViewBackend::~ViewBackend()
 {
-    unregisterSurface(m_bridgeId);
+    while (!m_bridgeIds.empty())
+        unregisterSurface(m_bridgeIds.front());
 
     if (m_clientFd != -1)
         close(m_clientFd);
@@ -92,10 +94,10 @@ void ViewBackend::exportEGLStreamProducer(struct wl_resource* bufferResource)
 
 void ViewBackend::dispatchFrameCallbacks()
 {
-    if (G_LIKELY(m_bridgeId))
-        WS::Instance::singleton().dispatchFrameCallbacks(m_bridgeId);
-
-    wpe_view_backend_dispatch_frame_displayed(m_backend);
+    if (G_LIKELY(!m_bridgeIds.empty())) {
+        WS::Instance::singleton().dispatchFrameCallbacks(m_bridgeIds.back());
+        wpe_view_backend_dispatch_frame_displayed(m_backend);
+    }
 }
 
 void ViewBackend::releaseBuffer(struct wl_resource* buffer_resource)
@@ -106,17 +108,18 @@ void ViewBackend::releaseBuffer(struct wl_resource* buffer_resource)
 
 void ViewBackend::registerSurface(uint32_t bridgeId)
 {
-    m_bridgeId = bridgeId;
-    WS::Instance::singleton().registerViewBackend(m_bridgeId, *this);
+    m_bridgeIds.push_back(bridgeId);
+    WS::Instance::singleton().registerViewBackend(m_bridgeIds.back(), *this);
 }
 
 void ViewBackend::unregisterSurface(uint32_t bridgeId)
 {
-    if (!bridgeId || m_bridgeId != bridgeId)
+    auto it = std::find(m_bridgeIds.begin(), m_bridgeIds.end(), bridgeId);
+    if (it == m_bridgeIds.end())
         return;
 
-    WS::Instance::singleton().unregisterViewBackend(m_bridgeId);
-    m_bridgeId = 0;
+    m_bridgeIds.erase(it);
+    WS::Instance::singleton().unregisterViewBackend(bridgeId);
 }
 
 void ViewBackend::didReceiveMessage(uint32_t messageId, uint32_t messageBody)

src/view-backend-private.h

@@ -30,6 +30,7 @@
 
 #include <gio/gio.h>
 #include <wpe/wpe.h>
+#include <vector>
 
 class ViewBackend;
 
@@ -78,7 +79,7 @@ class ViewBackend final : public WS::APIClient, public FdoIPC::MessageReceiver {
 
     static gboolean s_socketCallback(GSocket*, GIOCondition, gpointer);
 
-    uint32_t m_bridgeId { 0 };
+    std::vector<uint32_t> m_bridgeIds;
 
     ClientBundle* m_clientBundle;
     struct wpe_view_backend* m_backend;