Make sure Java Bridge cleans up all stub object it creates.

I have been trying to see why the JavaBridgeChannelHost, which is reference counted, sticks around forever.

Here is what I found:

When talk back is enabled. Each JavaBridgeChannelHost typically have 5 references to it. 3 of them should be cleaned up by this patch. (see comments in the .cc file)

BUG=157699


Review URL: https://chromiumcodereview.appspot.com/11359143

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@170694 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/renderer_host/java/java_bridge_dispatcher_host.cc

@@ -29,6 +29,15 @@ class JavaBridgeThread : public base::Thread {
     Stop();
   }
 };
+
+void CleanUpStubs(const std::vector<base::WeakPtr<NPObjectStub> > & stubs) {
+  for (size_t i = 0; i < stubs.size(); ++i) {
+    if (stubs[i]) {
+      stubs[i]->DeleteSoon();
+    }
+  }
+}
+
 base::LazyInstance<JavaBridgeThread> g_background_thread =
     LAZY_INSTANCE_INITIALIZER;
 }  // namespace
@@ -40,6 +49,9 @@ JavaBridgeDispatcherHost::JavaBridgeDispatcherHost(
 }
 
 JavaBridgeDispatcherHost::~JavaBridgeDispatcherHost() {
+  g_background_thread.Get().message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&CleanUpStubs, stubs_));
 }
 
 void JavaBridgeDispatcherHost::AddNamedObject(const string16& name,
@@ -133,13 +145,19 @@ void JavaBridgeDispatcherHost::CreateObjectStub(NPObject* object,
         BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO));
   }
 
-  // NPObjectStub takes a ref to the NPObject. The lifetime of the NPObjectStub
-  // is governed by that of the NPObjectProxy in the renderer, via the channel.
+  // In a typical scenario, the lifetime of each NPObjectStub is governed by
+  // that of the NPObjectProxy in the renderer, via the channel. However,
+  // we cannot guaranteed that the renderer always terminates cleanly
+  // (crashes / sometimes just unavoidable). We keep a weak reference to
+  // it now and schedule a delete on it when this host is getting deleted.
+
   // Pass 0 for the containing window, as it's only used by plugins to pump the
   // window message queue when a method on a renderer-side object causes a
   // dialog to be displayed, and the Java Bridge does not need this
   // functionality. The page URL is also not required.
-  new NPObjectStub(object, channel_, route_id, 0, GURL());
+  stubs_.push_back(
+      (new NPObjectStub(object, channel_, route_id, 0, GURL()))->AsWeakPtr());
+
   // The NPObjectStub takes a reference to the NPObject. Release the ref added
   // in CreateNPVariantParam().
   WebKit::WebBindings::releaseObject(object);

content/browser/renderer_host/java/java_bridge_dispatcher_host.h

@@ -5,8 +5,11 @@
 #ifndef CONTENT_BROWSER_RENDERER_HOST_JAVA_JAVA_BRIDGE_DISPATCHER_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_JAVA_JAVA_BRIDGE_DISPATCHER_HOST_H_
 
+#include <vector>
 #include "base/memory/ref_counted.h"
+#include "base/memory/weak_ptr.h"
 #include "base/string16.h"
+#include "content/common/npobject_stub.h"
 #include "content/public/browser/render_view_host_observer.h"
 
 class RouteIDGenerator;
@@ -62,6 +65,7 @@ class JavaBridgeDispatcherHost
 
   scoped_refptr<NPChannelBase> channel_;
   bool is_renderer_initialized_;
+  std::vector<base::WeakPtr<NPObjectStub> > stubs_;
 
   DISALLOW_COPY_AND_ASSIGN(JavaBridgeDispatcherHost);
 };