Browser Plugin: Implement BrowserPluginObserver.

content/public/renderer/browser_plugin/browser_plugin_observer.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/public/renderer/browser_plugin/browser_plugin_observer.h"
+
+#include "content/public/renderer/browser_plugin/browser_plugin.h"
+#include "content/renderer/browser_plugin/browser_plugin_impl.h"
+#include "ipc/ipc_message.h"
+
+namespace content {
+
+BrowserPluginObserver::BrowserPluginObserver(BrowserPlugin* browser_plugin)
+    : browser_plugin_(browser_plugin),
+      instance_id_(0) {
+  if (browser_plugin) {

[sadrul, 2013/01/09 15:21:54]

Once a BPO is created, it doesn't look like |browser_plugin_| can be changed at
a later time. If that is the case, should it ever be created with a null
browser-plugin? i.e. should CHECK here for a non-null browser-plugin?

[Fady Samuel, 2013/01/09 17:41:24]

It should never be null. Changed to a CHECK.

+    BrowserPluginImpl* impl = static_cast<BrowserPluginImpl*>(browser_plugin);
+    instance_id_ = impl->instance_id();
+    impl->AddObserver(this);
+  }
+}
+
+BrowserPluginObserver::~BrowserPluginObserver() {
+  if (browser_plugin_) {
+    BrowserPluginImpl* impl = static_cast<BrowserPluginImpl*>(browser_plugin_);
+    impl->RemoveObserver(this);
+  }
+}
+
+void BrowserPluginObserver::OnDestruct() {
+  delete this;
+}
+
+bool BrowserPluginObserver::OnMessageReceived(const IPC::Message& message) {
+  return false;
+}
+
+bool BrowserPluginObserver::Send(IPC::Message* message) {
+  if (browser_plugin_)
+    return browser_plugin_->Send(message);
+
+  delete message;
+  return false;
+}
+
+BrowserPlugin* BrowserPluginObserver::browser_plugin() const {
+  return browser_plugin_;
+}
+
+void BrowserPluginObserver::BrowserPluginGone() {
+  browser_plugin_ = NULL;

[sadrul, 2013/01/09 15:21:54]

Or perhaps allow setting the |browser_plugin_| of an observer (e.g. if an
observer overrides OnDestruct, and wants to be reused as an observer)?

[Fady Samuel, 2013/01/09 17:41:24]

I'd rather not, a BrowserPluginObserver can create
BrowserPluginMethod/PropertyBindings whose lifetime is tied to a particular
BrowserPlugin and refer back to a particular BrowserPluginObserver. I'm worried
that if we make it possible for an observer to change owner BrowserPlugins,
lifetime management might get confusing. I'd prefer to leave this as is, and add
additional functionality when necessary.

[sadrul, 2013/01/09 17:58:07]

Sounds good.

+}
+
+}  // namespace content