Log UpdateJumpList() and CreateIconFiles() execution time to UMA

The separation of JumpListIcons delete tasks and update tasks as in
crrev.com/2807883002 indicates the update task (i.e., RunUpdateJumpList
method) is now the major contributor of the overall long execution time.
So it's time to investigate the subtasks in RunUpdateJumpList().

The count of the new icon files that will be created per update is also
logged to UMA.

BUG=40407, 179576

Review-Url: https://codereview.chromium.org/2811393002
Cr-Commit-Position: refs/heads/master@{#464510}

chrome/browser/win/jumplist.cc

@@ -121,6 +121,9 @@ bool CreateIconFile(const gfx::ImageSkia& image_skia,
 // loaded icons.
 void CreateIconFiles(const base::FilePath& icon_dir,
                      const ShellLinkItemList& item_list) {
+  // TODO(chengx): Remove the UMA histogram after fixing http://crbug.com/40407.
+  SCOPED_UMA_HISTOGRAM_TIMER("WinJumplist.CreateIconFilesDuration");
+
   for (ShellLinkItemList::const_iterator item = item_list.begin();
       item != item_list.end(); ++item) {
     base::FilePath icon_path;
@@ -177,6 +180,9 @@ bool UpdateJumpList(const wchar_t* app_id,
                     const ShellLinkItemList& most_visited_pages,
                     const ShellLinkItemList& recently_closed_pages,
                     IncognitoModePrefs::Availability incognito_availability) {
+  // TODO(chengx): Remove the UMA histogram after fixing http://crbug.com/40407.
+  SCOPED_UMA_HISTOGRAM_TIMER("WinJumplist.UpdateJumpListDuration");
+
   // JumpList is implemented only on Windows 7 or later.
   // So, we should return now when this function is called on earlier versions
   // of Windows.
@@ -255,6 +261,12 @@ void RunUpdateJumpList(IncognitoModePrefs::Availability incognito_availability,
   // jumplist icons. The jumplist links should be updated anyway, as it doesn't
   // involve disk IO.
   if (base::DirectoryExists(icon_dir) && base::IsDirectoryEmpty(icon_dir)) {
+    // TODO(chengx): Remove the UMA histogram after fixing
+    // http://crbug.com/40407.
+    UMA_HISTOGRAM_COUNTS_100(
+        "WinJumplist.CreateIconFilesCount",
+        local_most_visited_pages.size() + local_recently_closed_pages.size());
+
     // Create icon files for shortcuts in the "Most Visited" category.
     CreateIconFiles(icon_dir, local_most_visited_pages);
 

tools/metrics/histograms/histograms.xml

@@ -81553,6 +81553,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>The type of category clicked in the Windows Jumplist</summary>
 </histogram>
 
+<histogram name="WinJumplist.CreateIconFilesCount">
+  <owner>chengx@chromium.org</owner>
+  <summary>
+    Count of jumplist icons that will be created per jumplist update. It is
+    recorded whenever UpdateJumpList() is called.
+  </summary>
+</histogram>
+
+<histogram name="WinJumplist.CreateIconFilesDuration" units="ms">
+  <owner>chengx@chromium.org</owner>
+  <summary>
+    Time spent in CreateIconFiles(). This method is called whenever there is a
+    jumplist update and the JumpListIcons folder is empty.
+  </summary>
+</histogram>
+
 <histogram name="WinJumplist.DeleteStatusJumpListIcons"
     enum="JumplisticonsDeleteCategory">
   <owner>chengx@chromium.org</owner>
@@ -81679,6 +81695,14 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WinJumplist.UpdateJumpListDuration" units="ms">
+  <owner>chengx@chromium.org</owner>
+  <summary>
+    Time spent in UpdateJumpList(). This method is called whenever there is a
+    jumplist update.
+  </summary>
+</histogram>
+
 <histogram name="WinTimeTicks.FailedToChangeCores" enum="WindowsVersion">
   <obsolete>
     Removed 01/2017.