Add PageLoad.* metrics for Offline Previews

chrome/browser/page_load_metrics/observers/previews_page_load_metrics_observer.h

 // Copyright 2016 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.
 
-#ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_DATA_REDUCTION_PROXY_METRICS_OBSERVER_H_
-#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_DATA_REDUCTION_PROXY_METRICS_OBSERVER_H_
-
-#include <memory>
+#ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_PAGE_LOAD_METRICS_OBSERVER_H_
+#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_PAGE_LOAD_METRICS_OBSERVER_H_
 
 #include "base/macros.h"
 #include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
 
 namespace content {
-class BrowserContext;
 class NavigationHandle;
+class WebContents;
 }
 
 namespace page_load_metrics {
 struct PageLoadExtraInfo;
 struct PageLoadTiming;
 }
 
-namespace data_reduction_proxy {
-class DataReductionProxyData;
-class DataReductionProxyPingbackClient;
+namespace previews {
 
 namespace internal {
 
-// Various UMA histogram names for DataReductionProxy core page load metrics.
-extern const char kHistogramDataReductionProxyPrefix[];
-extern const char kHistogramDataReductionProxyLoFiOnPrefix[];
+// Various UMA histogram names for Previews core page load metrics.
+extern const char kHistogramOfflinePreviewsPrefix[];
 extern const char kHistogramDOMContentLoadedEventFiredSuffix[];

[Charlie Harrison, 2016/08/19 20:00:22]

Are these metrics all needed? Do these need to directly compare with DRP
metrics? If you could, it would be great to trim this a bit (i.e. first
contentful paint, first image paint and first text paint are all very similar).

[RyanSturm, 2016/08/19 20:21:27]

Done.

 extern const char kHistogramFirstLayoutSuffix[];
 extern const char kHistogramLoadEventFiredSuffix[];
 extern const char kHistogramFirstContentfulPaintSuffix[];
 extern const char kHistogramFirstImagePaintSuffix[];
 extern const char kHistogramFirstPaintSuffix[];
 extern const char kHistogramFirstTextPaintSuffix[];
 extern const char kHistogramParseStartSuffix[];
 
 }  // namespace internal
 
-// Observer responsible for recording core page load metrics releveant to
-// DataReductionProxy.
-class DataReductionProxyMetricsObserver
+// Observer responsible for recording core page load metrics relevant to
+// Previews.
+class PreviewsPageLoadMetricsObserver
     : public page_load_metrics::PageLoadMetricsObserver {
  public:
-  DataReductionProxyMetricsObserver();
-  ~DataReductionProxyMetricsObserver() override;
+  PreviewsPageLoadMetricsObserver();
+  ~PreviewsPageLoadMetricsObserver() override;
 
   // page_load_metrics::PageLoadMetricsObserver:
   void OnCommit(content::NavigationHandle* navigation_handle) override;
-  void OnComplete(const page_load_metrics::PageLoadTiming& timing,
-                  const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnDomContentLoadedEventStart(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnLoadEventStart(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFirstLayout(const page_load_metrics::PageLoadTiming& timing,
                      const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFirstPaint(const page_load_metrics::PageLoadTiming& timing,
                     const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFirstTextPaint(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFirstImagePaint(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnFirstContentfulPaint(
       const page_load_metrics::PageLoadTiming& timing,
       const page_load_metrics::PageLoadExtraInfo& info) override;
   void OnParseStart(const page_load_metrics::PageLoadTiming& timing,
                     const page_load_metrics::PageLoadExtraInfo& info) override;
 
  private:
-  // Gets the default DataReductionProxyPingbackClient. Overridden in testing.
-  virtual DataReductionProxyPingbackClient* GetPingbackClient() const;
+  // Whether |web_contents| is showing an offline pages preview. Overridden in
+  // testing.
+  virtual bool IsOfflinePreview(content::WebContents* web_contents) const;
 
-  // Data related to this navigation.
-  std::unique_ptr<DataReductionProxyData> data_;
+  // Whether this page load was an offline pages preview.
+  bool is_offline_preview_;
 
-  // The browser context this navigation is operating in.
-  content::BrowserContext* browser_context_;
-
-  DISALLOW_COPY_AND_ASSIGN(DataReductionProxyMetricsObserver);
+  DISALLOW_COPY_AND_ASSIGN(PreviewsPageLoadMetricsObserver);
 };
 
-}  // namespace data_reduction_proxy
+}  // namespace previews
 
-#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_DATA_REDUCTION_PROXY_METRICS_OBSERVER_H_
+#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_PREVIEWS_PAGE_LOAD_METRICS_OBSERVER_H_