Log First User Interaction in Page Load Metrics

components/page_load_metrics/browser/metrics_web_contents_observer.cc

 // Copyright 2015 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 "components/page_load_metrics/browser/metrics_web_contents_observer.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram.h"
 #include "base/metrics/user_metrics.h"
 #include "components/page_load_metrics/browser/page_load_metrics_util.h"
 #include "components/page_load_metrics/common/page_load_metrics_messages.h"
 #include "components/page_load_metrics/common/page_load_timing.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_view_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
 #include "ui/base/page_transition_types.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(
     page_load_metrics::MetricsWebContentsObserver);
 
+class RenderViewHost;
+
 namespace page_load_metrics {
 
 namespace internal {
 
 const char kErrorEvents[] = "PageLoad.Events.InternalError";
 const char kAbortChainSizeReload[] =
     "PageLoad.Internal.ProvisionalAbortChainSize.Reload";
 const char kAbortChainSizeForwardBack[] =
     "PageLoad.Internal.ProvisionalAbortChainSize.ForwardBack";
 const char kAbortChainSizeNewNavigation[] =
@@ skipping 322 matching lines @@
     observer->OnFailedProvisionalLoad(navigation_handle);
   }
 }
 
 void PageLoadTracker::Redirect(content::NavigationHandle* navigation_handle) {
   for (const auto& observer : observers_) {
     observer->OnRedirect(navigation_handle);
   }
 }
 
+void PageLoadTracker::OnInputEvent(const blink::WebInputEvent& event) {
+  for (const auto& observer : observers_) {
+    observer->OnUserInput(event, navigation_start_ - base::TimeTicks::Now());
+  }
+}
+
 bool PageLoadTracker::UpdateTiming(const PageLoadTiming& new_timing,
                                    const PageLoadMetadata& new_metadata) {
   // Throw away IPCs that are not relevant to the current navigation.
   // Two timing structures cannot refer to the same navigation if they indicate
   // that a navigation started at different times, so a new timing struct with a
   // different start time from an earlier struct is considered invalid.
   bool valid_timing_descendent =
       timing_.navigation_start.is_null() ||
       timing_.navigation_start == new_timing.navigation_start;
   // Ensure flags sent previously are still present in the new metadata fields.
@@ skipping 116 matching lines @@
   abort_time_ = timestamp;
 }
 
 // static
 MetricsWebContentsObserver::MetricsWebContentsObserver(
     content::WebContents* web_contents,
     std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface)
     : content::WebContentsObserver(web_contents),
       in_foreground_(false),
       embedder_interface_(std::move(embedder_interface)),
-      has_navigated_(false) {}
+      has_navigated_(false) {
+  this->RegisterInputEventObserver(web_contents->GetRenderViewHost());
+}
 
 MetricsWebContentsObserver* MetricsWebContentsObserver::CreateForWebContents(
     content::WebContents* web_contents,
     std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface) {
   DCHECK(web_contents);
 
   MetricsWebContentsObserver* metrics = FromWebContents(web_contents);
   if (!metrics) {
     metrics = new MetricsWebContentsObserver(web_contents,
                                              std::move(embedder_interface));
     web_contents->SetUserData(UserDataKey(), metrics);
   }
   return metrics;
 }
 
 MetricsWebContentsObserver::~MetricsWebContentsObserver() {
   NotifyAbortAllLoads(ABORT_CLOSE);
+  UnregisterInputEventObserver(web_contents()->GetRenderViewHost());

[Charlie Harrison, 2016/05/27 18:14:34]

Hm this feels unsafe. I don't think we should be calling web_contents() in the
destructor. I think the last possible place you can safely call this is in
WebContentsDestroyed() or something. Can you verify?

[mushan1, 2016/05/27 18:51:24]

What do you think if we just remove this Unregister logic? Since if
web_contents() are destroyed, there won't be further callbacks triggered.
Could a page load metrics observer live longer than its web_contents?

[Charlie Harrison, 2016/05/27 18:58:24]

No, currently observers are scoped to the WebContentsObserver, which is scoped
to the WebContents. I'm fine with removing the unregister logic if it's safe.
Note that you'll need to be sure that the RenderWidgetHost does not outlive the
WebContents. I'm not 100% sure of that.

[mushan1, 2016/05/27 19:38:11]

refer to
https://code.google.com/p/chromium/codesearch#chromium/src/content/public/bro...

The case RenderWidgetHost outlives WebContents does not apply here (WebContents
does not have its reference anyway).

Removed the unregister logic.

+}
+
+void MetricsWebContentsObserver::RegisterInputEventObserver(
+    content::RenderViewHost* host) {
+  host->GetWidget()->AddInputEventObserver(this);
+}
+
+void MetricsWebContentsObserver::UnregisterInputEventObserver(
+    content::RenderViewHost* host) {
+  host->GetWidget()->RemoveInputEventObserver(this);
+}
+
+void MetricsWebContentsObserver::RenderViewHostChanged(
+    content::RenderViewHost* old_host,
+    content::RenderViewHost* new_host) {
+  UnregisterInputEventObserver(old_host);
+  RegisterInputEventObserver(new_host);
 }
 
 bool MetricsWebContentsObserver::OnMessageReceived(
     const IPC::Message& message,
     content::RenderFrameHost* render_frame_host) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP_WITH_PARAM(MetricsWebContentsObserver, message,
                                    render_frame_host)
     IPC_MESSAGE_HANDLER(PageLoadMetricsMsg_TimingUpdated, OnTimingUpdated)
@@ skipping 117 matching lines @@
   committed_load_->set_renderer_tracked(
       IsRelevantNavigation(navigation_handle, browser_url, mime_type));
 
   committed_load_->Commit(navigation_handle);
 }
 
 void MetricsWebContentsObserver::NavigationStopped() {
   NotifyAbortAllLoads(ABORT_STOP);
 }
 
+bool MetricsWebContentsObserver::OnInputEvent(
+    const blink::WebInputEvent& event) {
+  // Ignore browser navigation or reload which comes with type Undefined.
+  if (event.type == blink::WebInputEvent::Type::Undefined)
+    return false;
+
+  if (!committed_load_) {
+    RecordInternalError(ERR_USER_INPUT_WITH_NO_RELEVANT_LOAD);
+    return false;
+  }
+
+  committed_load_->OnInputEvent(event);
+  return true;
+}
+
 void MetricsWebContentsObserver::DidRedirectNavigation(
     content::NavigationHandle* navigation_handle) {
   if (!navigation_handle->IsInMainFrame())
     return;
   auto it = provisional_loads_.find(navigation_handle);
   if (it == provisional_loads_.end())
     return;
   it->second->Redirect(navigation_handle);
 }
 
@@ skipping 112 matching lines @@
 
   if (!committed_load_->UpdateTiming(timing, metadata)) {
     // If the page load tracker cannot update its timing, something is wrong
     // with the IPC (it's from another load, or it's invalid in some other way).
     // We expect this to be a rare occurrence.
     RecordInternalError(ERR_BAD_TIMING_IPC);
   }
 }
 
 }  // namespace page_load_metrics