UMA for measuring how often 2 or more tabs script the same background contents.

chrome/browser/background/background_contents.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 "chrome/browser/background/background_contents.h"
 
 #include <utility>
 
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/profiler/scoped_tracker.h"
 #include "chrome/browser/background/background_contents_service.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/data_use_measurement/data_use_web_contents_observer.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/renderer_preferences_util.h"
 #include "chrome/browser/task_manager/web_contents_tags.h"
 #include "chrome/browser/ui/webui/chrome_web_ui_controller_factory.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/session_storage_namespace.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
 #include "extensions/browser/deferred_start_render_host_observer.h"
 #include "extensions/browser/extension_host_delegate.h"
 #include "extensions/browser/extension_host_queue.h"
+#include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extensions_browser_client.h"
 #include "extensions/browser/view_type_utils.h"
 #include "ui/gfx/geometry/rect.h"
 
 using content::SiteInstance;
 using content::WebContents;
 
 BackgroundContents::BackgroundContents(
     scoped_refptr<SiteInstance> site_instance,
     content::RenderFrameHost* opener,
     int32_t routing_id,
     int32_t main_frame_routing_id,
     int32_t main_frame_widget_routing_id,
     Delegate* delegate,
     const std::string& partition_id,
     content::SessionStorageNamespace* session_storage_namespace)
     : delegate_(delegate),
       extension_host_delegate_(extensions::ExtensionsBrowserClient::Get()
-                                   ->CreateExtensionHostDelegate()) {
+                                   ->CreateExtensionHostDelegate()),
+      weak_factory_(this) {
   profile_ = Profile::FromBrowserContext(
       site_instance->GetBrowserContext());
 
   WebContents::CreateParams create_params(profile_, std::move(site_instance));
   create_params.opener_render_process_id =
       opener ? opener->GetProcess()->GetID() : MSG_ROUTING_NONE;
   create_params.opener_render_frame_id =
       opener ? opener->GetRoutingID() : MSG_ROUTING_NONE;
   create_params.routing_id = routing_id;
   create_params.main_frame_routing_id = main_frame_routing_id;
   create_params.main_frame_widget_routing_id = main_frame_widget_routing_id;
   create_params.renderer_initiated_creation = routing_id != MSG_ROUTING_NONE;
   if (session_storage_namespace) {
     content::SessionStorageNamespaceMap session_storage_namespace_map;
     session_storage_namespace_map.insert(
         std::make_pair(partition_id, session_storage_namespace));
     web_contents_.reset(WebContents::CreateWithSessionStorage(
         create_params, session_storage_namespace_map));
   } else {
     web_contents_.reset(WebContents::Create(create_params));
   }
+  TrackPreviousOpener();
   extensions::SetViewType(
       web_contents_.get(), extensions::VIEW_TYPE_BACKGROUND_CONTENTS);
   web_contents_->SetDelegate(this);
   content::WebContentsObserver::Observe(web_contents_.get());
   data_use_measurement::DataUseWebContentsObserver::CreateForWebContents(
       web_contents_.get());
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       web_contents_.get());
 
   // Add the TaskManager-specific tag for the BackgroundContents.
   task_manager::WebContentsTags::CreateForBackgroundContents(
       web_contents_.get(), this);
 
   // Close ourselves when the application is shutting down.
   registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
                  content::NotificationService::AllSources());
 
   // Register for our parent profile to shutdown, so we can shut ourselves down
   // as well (should only be called for OTR profiles, as we should receive
   // APP_TERMINATING before non-OTR profiles are destroyed).
   registrar_.Add(this, chrome::NOTIFICATION_PROFILE_DESTROYED,
                  content::Source<Profile>(profile_));
 }
 
 // Exposed to allow creating mocks.
 BackgroundContents::BackgroundContents()
-    : delegate_(NULL),
-      profile_(NULL) {
-}
+    : delegate_(NULL), profile_(NULL), weak_factory_(this) {}
 
 BackgroundContents::~BackgroundContents() {
   if (!web_contents_.get())   // Will be null for unit tests.
     return;
 
   // Unregister for any notifications before notifying observers that we are
   // going away - this prevents any re-entrancy due to chained notifications
   // (http://crbug.com/237781).
   registrar_.RemoveAll();
 
@@ skipping 115 matching lines @@
 
 void BackgroundContents::AddDeferredStartRenderHostObserver(
     extensions::DeferredStartRenderHostObserver* observer) {
   deferred_start_render_host_observer_list_.AddObserver(observer);
 }
 
 void BackgroundContents::RemoveDeferredStartRenderHostObserver(
     extensions::DeferredStartRenderHostObserver* observer) {
   deferred_start_render_host_observer_list_.RemoveObserver(observer);
 }
+
+namespace {
+
+class OpenerDestroyedObserver : public content::WebContentsObserver {
+ public:
+  OpenerDestroyedObserver(content::RenderFrameHost* opener,
+                          base::OnceClosure callback)
+      : WebContentsObserver(WebContents::FromRenderFrameHost(opener)),
+        opener_(opener),
+        callback_(std::move(callback)) {
+    DCHECK(!callback_.is_null());
+  }
+
+  // WebContentsObserver override:
+  void RenderFrameDeleted(content::RenderFrameHost* deleted_frame) override {
+    if (deleted_frame == opener_) {
+      std::move(callback_).Run();
+      delete this;
+    }
+  }
+
+ private:
+  content::RenderFrameHost* opener_;
+  base::OnceClosure callback_;
+  DISALLOW_COPY_AND_ASSIGN(OpenerDestroyedObserver);
+};
+
+}  // namespace
+
+void BackgroundContents::TrackPreviousOpener() {
+  // Do we already have a still-alive previous opener that is a hosted app?
+  if (previous_opener_)
+    return;
+
+  if (!IsCurrentOpenerHostedApp())
+    return;
+
+  previous_opener_ = web_contents()->GetOpener();
+  DCHECK(previous_opener_);
+  new OpenerDestroyedObserver(
+      previous_opener_,
+      base::Bind(&BackgroundContents::OnPreviousOpenerDestroyed,
+                 weak_factory_.GetWeakPtr()));
+}
+
+void BackgroundContents::OnPreviousOpenerDestroyed() {
+  previous_opener_ = nullptr;
+}
+
+bool BackgroundContents::IsCurrentOpenerHostedApp() {
+  content::RenderFrameHost* current_opener = web_contents()->GetOpener();
+  if (!current_opener)
+    return false;
+
+  const extensions::Extension* opener_extension =
+      extensions::ExtensionRegistry::Get(web_contents()->GetBrowserContext())
+          ->enabled_extensions()
+          .GetExtensionOrAppByURL(current_opener->GetLastCommittedURL());
+  return opener_extension && opener_extension->is_hosted_app();
+}
+
+void BackgroundContents::DidChangeOpener() {
+  if (previous_opener_ && IsCurrentOpenerHostedApp() &&
+      (web_contents()->GetOpener() != previous_opener_)) {
+    UMA_HISTOGRAM_BOOLEAN(
+        "Extensions.HostedAppOpenedBackgroundContentsFromTwoOpeners", true);
+  }
+
+  TrackPreviousOpener();
+}