Read later: add WebuiLoadTimer metrics.

Bug: 1163938
Change-Id: I03c223c41de3196be12d9d4283087dfa04ec38e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2621676Reviewed-by: Connie Wan <connily@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Caroline Rising <corising@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842384}

chrome/browser/ui/webui/read_later/read_later_ui.cc

@@ -34,7 +34,10 @@ void AddLocalizedString(content::WebUIDataSource* source,
 }  // namespace
 
 ReadLaterUI::ReadLaterUI(content::WebUI* web_ui)
-    : ui::MojoBubbleWebUIController(web_ui) {
+    : ui::MojoBubbleWebUIController(web_ui),
+      webui_load_timer_(web_ui->GetWebContents(),
+                        "ReadingList.WebUI.LoadDocumentTime",
+                        "ReadingList.WebUI.LoadCompletedTime") {
   content::WebUIDataSource* source =
       content::WebUIDataSource::Create(chrome::kChromeUIReadLaterHost);
   static constexpr webui::LocalizedString kLocalizedStrings[] = {

chrome/browser/ui/webui/read_later/read_later_ui.h

@@ -9,6 +9,7 @@
 
 #include "base/macros.h"
 #include "chrome/browser/ui/webui/read_later/read_later.mojom.h"
+#include "chrome/browser/ui/webui/webui_load_timer.h"
 #include "mojo/public/cpp/bindings/pending_receiver.h"
 #include "mojo/public/cpp/bindings/pending_remote.h"
 #include "mojo/public/cpp/bindings/receiver.h"
@@ -40,6 +41,8 @@ class ReadLaterUI : public ui::MojoBubbleWebUIController,
   mojo::Receiver<read_later::mojom::PageHandlerFactory> page_factory_receiver_{
       this};
 
+  WebuiLoadTimer webui_load_timer_;
+
   WEB_UI_CONTROLLER_TYPE_DECL();
 };
 

tools/metrics/histograms/histograms_xml/others/histograms.xml

@@ -12676,6 +12676,27 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
   <summary>Number of unread entries in reading list.</summary>
 </histogram>
 
+<histogram name="ReadingList.WebUI.LoadCompletedTime" units="ms"
+    expires_after="M92">
+  <owner>corising@chromium.org</owner>
+  <owner>chrome-desktop-ui-sea@google.com</owner>
+  <summary>
+    The amount of time between the render frame host StartProvisionalLoad event
+    and the render frame DocumentOnLoadCompleted event for the Read Later WebUI
+    page.
+  </summary>
+</histogram>
+
+<histogram name="ReadingList.WebUI.LoadDocumentTime" units="ms"
+    expires_after="M92">
+  <owner>corising@chromium.org</owner>
+  <owner>chrome-desktop-ui-sea@google.com</owner>
+  <summary>
+    The amount of time between the render frame host StartProvisionalLoad and
+    DidFinishDocumentLoad events for the Read Later WebUI page.
+  </summary>
+</histogram>
+
 <histogram name="RecoveryComponent.Event" enum="RecoveryComponentEvent"
     expires_after="M77">
   <owner>robertshield@chromium.org</owner>