Add a way to send the resource percentage signal to the RC.

chrome/browser/offline_pages/background_loader_offliner.cc

Index: chrome/browser/offline_pages/background_loader_offliner.cc
diff --git a/chrome/browser/offline_pages/background_loader_offliner.cc b/chrome/browser/offline_pages/background_loader_offliner.cc
index 6cc5f3d0fd5de7c4d71000927dc4948a3f6a4bcc..6e7609afae1eefae704761fabe77f1bd996737a0 100644
--- a/chrome/browser/offline_pages/background_loader_offliner.cc
+++ b/chrome/browser/offline_pages/background_loader_offliner.cc
@@ -12,6 +12,8 @@
 #include "base/time/time.h"
 #include "chrome/browser/android/offline_pages/offline_page_mhtml_archiver.h"
 #include "chrome/browser/android/offline_pages/offliner_helper.h"
+#include "chrome/browser/offline_pages/offliner_user_data.h"
+#include "chrome/browser/page_load_metrics/page_load_metrics_initialize.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/offline_pages/core/background/offliner_policy.h"
 #include "components/offline_pages/core/background/save_page_request.h"
@@ -33,28 +35,6 @@ const char kContentTransferEncodingBinary[] =
     "Content-Transfer-Encoding: binary";
 const char kXHeaderForSignals[] = "X-Chrome-Loading-Metrics-Data: 1";
 
-class OfflinerData : public content::WebContentsUserData<OfflinerData> {
- public:
-  static void AddToWebContents(content::WebContents* webcontents,
-                               BackgroundLoaderOffliner* offliner) {
-    DCHECK(offliner);
-    webcontents->SetUserData(UserDataKey(), std::unique_ptr<OfflinerData>(
-                                                new OfflinerData(offliner)));
-  }
-
-  explicit OfflinerData(BackgroundLoaderOffliner* offliner) {
-    offliner_ = offliner;
-  }
-  BackgroundLoaderOffliner* offliner() { return offliner_; }
-
- private:
-  // The offliner that the WebContents is attached to. The offliner owns the
-  // Delegate which owns the WebContents that this data is attached to.
-  // Therefore, its lifetime should exceed that of the WebContents, so this
-  // should always be non-null.
-  BackgroundLoaderOffliner* offliner_;
-};
-
 std::string AddHistogramSuffix(const ClientId& client_id,
                                const char* histogram_name) {
   if (client_id.name_space.empty()) {
@@ -105,9 +85,12 @@ BackgroundLoaderOffliner::~BackgroundLoaderOffliner() {}
 // static
 BackgroundLoaderOffliner* BackgroundLoaderOffliner::FromWebContents(
     content::WebContents* contents) {
-  OfflinerData* data = OfflinerData::FromWebContents(contents);
-  if (data)
-    return data->offliner();
+  Offliner* offliner = OfflinerUserData::OfflinerFromWebContents(contents);
+
+  // Today we only have one kind of offliner that uses OfflinerUserData.  If we
+  // add other types, revisit this cast.
+  if (offliner)
+    return static_cast<BackgroundLoaderOffliner*>(offliner);
   return nullptr;
 }
 
@@ -238,6 +221,15 @@ bool BackgroundLoaderOffliner::HandleTimeout(int64_t request_id) {
   return false;
 }
 
+void BackgroundLoaderOffliner::ObserveResourceTracking(
+    const ResourceDataType type,
+    int64_t started_count,
+    int64_t completed_count) {
+  // Add the signal to extra data, and use for tracking.
+  if (type == ResourceDataType::IMAGE)
+    AddResourceSignal(type, started_count, completed_count);
+}
+
 void BackgroundLoaderOffliner::MarkLoadStartTime() {
   load_start_time_ = base::TimeTicks::Now();
 }
@@ -465,7 +457,12 @@ void BackgroundLoaderOffliner::ResetLoader() {
 void BackgroundLoaderOffliner::AttachObservers() {
   content::WebContents* contents = loader_->web_contents();
   content::WebContentsObserver::Observe(contents);
-  OfflinerData::AddToWebContents(contents, this);
+  OfflinerUserData::AddToWebContents(contents, this);
+
+  // Attach the metrics observers to the web contents so we can get resoure
+  // loading signals.
+  chrome::InitializePageLoadMetricsForWebContents(

[Bryan McQuade, 2017/05/23 05:00:01]

do we want to bring up the full page load metrics infrastructure, including all
observers, for this background loader offliner mode? My sense is we probably
don't want to do this - for example I don't think we want to be recording core
page load metrics for this context. In general we only want to bring up the page
load metrics infrastructure for tabs that are actually being displayed to users.
On first glance, I think this is probably out of scope for page load metrics.

I'll need to look at this change in a bit more detail to better understand the
goals & constraints - will try to follow up soon.

[Pete Williamson, 2017/05/24 01:01:50]

As the code is written now, InitializePageLoadMetricsForWebContents will only
initialize the observers that we use while doing background offlining, instead
of all of them. 

My intent moving forwards is to leverage other page load metrics for right
moment detection.  We've talked before about using the FirstMeaningfulPaint and
TimeToInteractive(once it is available) metrics.

+      contents, true /* background loading */);
 }
 
 void BackgroundLoaderOffliner::OnApplicationStateChange(
@@ -493,6 +490,15 @@ void BackgroundLoaderOffliner::AddLoadingSignal(const char* signal_name) {
   signal_data_.SetDouble(signal_name, delay);
 }
 
-}  // namespace offline_pages
+void BackgroundLoaderOffliner::AddResourceSignal(const ResourceDataType type,
+                                                 int64_t started_count,
+                                                 int64_t completed_count) {
+  double percentage = 100.0 * static_cast<double>(completed_count) /

[Dmitry Titov, 2017/05/18 02:28:10]

Not clear why do we need the percentage here in addition to started/completed.
It is always computable if needed later.

[Pete Williamson, 2017/05/24 01:01:50]

OK, removed percentage.

+                      static_cast<double>(started_count);
+  // TODO(petewil): Use actual signal type instead of hardcoding name to image.
+  signal_data_.SetDouble("ImagePercentage", percentage);
+  signal_data_.SetDouble("StartedImages", started_count);
+  signal_data_.SetDouble("CompletedImages", completed_count);
+}
 
-DEFINE_WEB_CONTENTS_USER_DATA_KEY(offline_pages::OfflinerData);
+}  // namespace offline_pages