PageLoadMetrics renderer and browser implementation.

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 "base/logging.h"
+#include "base/metrics/histogram.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/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"
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(
+    page_load_metrics::MetricsWebContentsObserver);
+
+namespace page_load_metrics {
+
+namespace {
+
+bool IsValidPageLoadTiming(const PageLoadTiming& timing) {
+  if (timing.IsEmpty())
+    return false;
+
+  // If we have a non-empty timing, it should always have a navigation start.
+  if (timing.navigation_start.is_null())
+    return false;
+
+  // If we have a dom content loaded event, we should have a response start.
+  if (!timing.dom_content_loaded_event_start.is_zero()) {
+    if (timing.response_start.is_zero() ||
+        timing.dom_content_loaded_event_start < timing.response_start) {
+      return false;
+    }
+  }
+
+  // If we have a load event, we should have both a response start and a DCL.
+  if (!timing.load_event_start.is_zero()) {
+    if (timing.response_start.is_zero() ||
+        timing.dom_content_loaded_event_start.is_zero() ||
+        timing.load_event_start < timing.dom_content_loaded_event_start ||
+        timing.load_event_start < timing.response_start) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+}  // namespace
+MetricsWebContentsObserver::MetricsWebContentsObserver(
+    content::WebContents* web_contents)
+    : content::WebContentsObserver(web_contents) {}

[Bryan McQuade, 2015/09/10 22:32:53]

should add:
current_host_(nullptr)
in the initializer list

[Charlie Harrison, 2015/09/11 14:40:52]

Done.

+
+// As a tab helper, this object is tied to a single WebContent
+// for its entire lifetime.
+MetricsWebContentsObserver::~MetricsWebContentsObserver() {
+  RecordTimingHistograms();
+}
+
+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)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void MetricsWebContentsObserver::DidCommitNavigation(
+    content::NavigationHandle* navigation_handle) {
+  if (navigation_handle->IsInMainFrame() && !navigation_handle->IsSamePage())
+    RecordTimingHistograms();
+  if (IsRelevantNavigation(navigation_handle)) {
+    current_timing_.reset(new PageLoadTiming());
+  }
+}
+
+// This will occur when the process for the main RenderFrameHost exits.
+// This will happen with a normal exit or a crash.
+void MetricsWebContentsObserver::RenderProcessGone(
+    base::TerminationStatus status) {
+  RecordTimingHistograms();
+}
+
+#define PAGE_LOAD_HISTOGRAM(name, sample)                           \
+  UMA_HISTOGRAM_CUSTOM_TIMES(name, sample,                          \
+                             base::TimeDelta::FromMilliseconds(10), \
+                             base::TimeDelta::FromMinutes(10), 100);
+
+void MetricsWebContentsObserver::OnTimingUpdated(
+    content::RenderFrameHost* render_frame_host,
+    const PageLoadTiming& timing) {
+  if (!current_timing_)
+    return;
+
+  // We may receive notifications from frames that have been navigated away
+  // from. We simply ignore them.
+  if (render_frame_host != web_contents()->GetMainFrame())
+    return;
+
+  // See comment in IsRelevantNavigation about
+  // browser/renderer url disagreement (newtab).
+  if (!web_contents()->GetLastCommittedURL().SchemeIsHTTPOrHTTPS())
+    return;
+
+  // Throw away IPCs that are not relevant to the current navigation.
+  if (!current_timing_->navigation_start.is_null() &&
+      timing.navigation_start != current_timing_->navigation_start) {
+    // TODO(csharrison) uma log a counter here
+    return;
+  }
+
+  if (current_timing_->IsEmpty())
+    current_host_ = render_frame_host;

[Bryan McQuade, 2015/09/10 22:32:53]

We should be resetting current_host_ = nullptr before the RFH gets deleted. As
your code is written today it's fine since you don't use current_host_ for
anything other than equality tests, but it's best to be defensive and make sure
we don't have pointers pointing at invalid memory, in case someone decides to
use current_host_ for something else in the future.

Maybe add an override of the FrameDeleted method:

void MetricsWebContentsObserver::FrameDeleted(RenderFrameHost*
render_frame_host) {
  if (render_frame_host == current_host_)
    current_host_ = nullptr;
}

[Charlie Harrison, 2015/09/11 14:40:52]

Done.

+  else
+    DCHECK_EQ(render_frame_host, current_host_);
+  *current_timing_ = timing;
+}
+
+void MetricsWebContentsObserver::RecordTimingHistograms() {
+  if (!current_timing_ || !IsValidPageLoadTiming(*current_timing_))
+    return;
+
+  if (!current_timing_->dom_content_loaded_event_start.is_zero()) {
+    PAGE_LOAD_HISTOGRAM(
+        "PageLoadTiming.Navigation.To.DOMContentLoadedEventFired",
+        current_timing_->dom_content_loaded_event_start);
+  }
+
+  if (!current_timing_->load_event_start.is_zero()) {
+    PAGE_LOAD_HISTOGRAM(
+        "PageLoadTiming.Navigation.To.LoadEventFired",
+        current_timing_->load_event_start);
+  }
+
+  if (!current_timing_->first_layout.is_zero()) {
+    PAGE_LOAD_HISTOGRAM(
+        "PageLoadTiming.Navigation.To.FirstLayout",
+        current_timing_->first_layout);
+  }
+  current_timing_.reset();
+}
+
+bool MetricsWebContentsObserver::IsRelevantNavigation(
+    content::NavigationHandle* navigation_handle) {
+  // The url we see from the renderer side is not always the same as what
+  // we see from the browser side (e.g. chrome://newtab). We want to be
+  // sure here that we aren't logging UMA for internal pages.
+  const GURL& browser_url = web_contents()->GetLastCommittedURL();
+      return navigation_handle->IsInMainFrame() &&
+         !navigation_handle->IsSamePage() &&
+         navigation_handle->HasCommittedDocument() &&
+         navigation_handle->GetURL().SchemeIsHTTPOrHTTPS() &&
+         browser_url.SchemeIsHTTPOrHTTPS();
+}
+
+}  // namespace page_load_metrics