Move lazy event dispatching code out of EventRouter.

extensions/browser/events/lazy_event_dispatcher.cc

Index: extensions/browser/events/lazy_event_dispatcher.cc
diff --git a/extensions/browser/events/lazy_event_dispatcher.cc b/extensions/browser/events/lazy_event_dispatcher.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4e0d3533548a5deb80e7436b0503706f7c3e4795
--- /dev/null
+++ b/extensions/browser/events/lazy_event_dispatcher.cc
@@ -0,0 +1,137 @@
+// Copyright 2017 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 "extensions/browser/events/lazy_event_dispatcher.h"
+
+#include "base/bind.h"
+#include "base/memory/ptr_util.h"
+#include "extensions/browser/event_router.h"
+#include "extensions/browser/extension_registry.h"
+#include "extensions/browser/extensions_browser_client.h"
+#include "extensions/browser/lazy_background_task_queue.h"
+#include "extensions/browser/lazy_context_id.h"
+#include "extensions/common/manifest_handlers/incognito_info.h"
+
+using content::BrowserContext;
+
+namespace extensions {
+
+LazyEventDispatcher::LazyEventDispatcher(
+    BrowserContext* browser_context,
+    const linked_ptr<Event>& event,
+    const DispatchFunction& dispatch_function)
+    : browser_context_(browser_context),
+      event_(event),
+      dispatch_function_(dispatch_function) {}
+
+LazyEventDispatcher::~LazyEventDispatcher() {}
+
+void LazyEventDispatcher::DispatchToEventPage(
+    const ExtensionId& extension_id,
+    const base::DictionaryValue* listener_filter) {
+  LazyContextId dispatch_context(browser_context_, extension_id);
+  DispatchToLazyContext(&dispatch_context, listener_filter);
+}
+
+bool LazyEventDispatcher::HasAlreadyDispatched(
+    BrowserContext* context,
+    const EventListener* listener) const {
+  auto dispatch_context =
+      base::MakeUnique<LazyContextId>(context, listener->extension_id());
+  return HasAlreadyDispatchedImpl(dispatch_context.get());
+}
+
+void LazyEventDispatcher::DispatchToLazyContext(
+    LazyContextId* dispatch_context,
+    const base::DictionaryValue* listener_filter) {
+  const Extension* extension = ExtensionRegistry::Get(browser_context_)
+                                   ->enabled_extensions()
+                                   .GetByID(dispatch_context->extension_id());
+  if (!extension)
+    return;
+
+  // Check both the original and the incognito browser context to see if we
+  // should load a non-peristent context (a lazy background page or an
+  // extension service worker) to handle the event. The latter case

[Devlin, 2017/06/15 15:09:50]

nit: with the addition of the "a lazy background page or an extension service
worker" piece, which "latter" this is referring to (either incognito context or
extension service worker) becomes ambiguous.  Maybe s/The latter case occurs/We
need to use the incognito context/?

[lazyboy, 2017/06/15 17:33:51]

Done.

+  // occurs in the case of split-mode extensions.
+  if (QueueEventDispatch(dispatch_context, extension, listener_filter))
+    RecordAlreadyDispatched(dispatch_context);
+
+  BrowserContext* additional_context = GetIncognitoContext(extension);
+  if (!additional_context)
+    return;
+
+  dispatch_context->set_browser_context(additional_context);
+  if (QueueEventDispatch(dispatch_context, extension, listener_filter))
+    RecordAlreadyDispatched(dispatch_context);
+}
+
+bool LazyEventDispatcher::QueueEventDispatch(
+    LazyContextId* dispatch_context,
+    const Extension* extension,
+    const base::DictionaryValue* listener_filter) {
+  if (!EventRouter::CanDispatchEventToBrowserContext(
+          dispatch_context->browser_context(), extension, *event_)) {
+    return false;
+  }
+
+  if (HasAlreadyDispatchedImpl(dispatch_context))
+    return false;
+
+  LazyBackgroundTaskQueue* queue = dispatch_context->GetTaskQueue();
+  if (!queue->ShouldEnqueueTask(dispatch_context->browser_context(),
+                                extension)) {
+    return false;
+  }
+
+  linked_ptr<Event> dispatched_event(event_);
+
+  // If there's a dispatch callback, call it now (rather than dispatch time)
+  // to avoid lifetime issues. Use a separate copy of the event args, so they
+  // last until the event is dispatched.
+  if (!event_->will_dispatch_callback.is_null()) {
+    dispatched_event.reset(event_->DeepCopy());
+    if (!dispatched_event->will_dispatch_callback.Run(
+            dispatch_context->browser_context(), extension,
+            dispatched_event.get(), listener_filter)) {
+      // The event has been canceled.
+      return true;
+    }
+    // Ensure we don't call it again at dispatch time.
+    dispatched_event->will_dispatch_callback.Reset();
+  }
+
+  queue->AddPendingTask(dispatch_context->browser_context(),
+                        dispatch_context->extension_id(),
+                        base::Bind(dispatch_function_, dispatched_event));
+
+  return true;
+}
+
+bool LazyEventDispatcher::HasAlreadyDispatchedImpl(
+    const LazyContextId* dispatch_context) const {
+  DCHECK(dispatch_context->is_for_event_page());
+  EventPageDispatchIdentifier dispatch_id(dispatch_context->browser_context(),
+                                          dispatch_context->extension_id());
+  return base::ContainsKey(dispatched_ids_for_event_page_, dispatch_id);
+}
+
+void LazyEventDispatcher::RecordAlreadyDispatched(
+    LazyContextId* dispatch_context) {
+  DCHECK(dispatch_context->is_for_event_page());
+  dispatched_ids_for_event_page_.insert(std::make_pair(
+      dispatch_context->browser_context(), dispatch_context->extension_id()));
+}
+
+BrowserContext* LazyEventDispatcher::GetIncognitoContext(
+    const Extension* extension) {
+  if (!IncognitoInfo::IsSplitMode(extension))
+    return nullptr;
+  ExtensionsBrowserClient* browser_client = ExtensionsBrowserClient::Get();
+  if (!browser_client->HasOffTheRecordContext(browser_context_))
+    return nullptr;
+  return browser_client->GetOffTheRecordContext(browser_context_);
+}
+
+}  // namespace extensions