Bug 525946 [Webkit2] Port download functionality (rewrite some logic)

G_TYPE_CHECK_INSTANCE_TYPE is not a reliable method to check
if type is webview or webcontext at run time.
On my & Roland's system it works, but on Andrey's system it
miss-fires.
This is a macro and by the looks is not reliable method because
we use it with dynamically loaded libraries and via JNI.

Solution:
Rewrite the callback logic to determine types of callback based on
user_data instead of relying on type checking macro.

Also, created task to remove usage of the macro to prevent simmila
issues:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=533833

Tests:
- Environment: Webkit2 2.18, Gtk3.22, Fedora 27, wayland on host, x11
eclipse backend.
- JUnit AllBrowserTests
- ChildEclipse.
- Bug Snippet attached to this patch.
- Also tested with webkit1.
- Andrey reports that this patch fixes his crash issue:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=533545#c34

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=5259462
Change-Id: I485a54804285dbf114961422799ea34796413404
Signed-off-by: Leo Ufimtsev <lufimtse@redhat.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java b/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
index ec0375a0c2..b2cb13fe65 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT PI/gtk/org/eclipse/swt/internal/gtk/OS.java
@@ -1089,6 +1089,12 @@ public static final long /*int*/ G_OBJECT_TYPE_NAME (long /*int*/ object) {
 		lock.unlock();
 	}
 }
+
+/**
+ * This method is not a reliable way to test for a type.
+ *  Use G_OBJECT_TYPE type instead or use alternate means (e.g custom userdata).
+ *  TODO: remove usage of this call.
+ */
 public static final native boolean _G_TYPE_CHECK_INSTANCE_TYPE (long /*int*/ instance, long /*int*/ type);
 public static final boolean G_TYPE_CHECK_INSTANCE_TYPE (long /*int*/ instance, long /*int*/ type) {
 	lock.lock();