Log basic tab strip paint performance metrics

This add a metric for tracking time spent painting the TabStrip at a
high level and another for time spent painting TabIcons. The former is
logged for each frame the TabStrip paints. The latter is logged every
time a TabIcon paints, which can be more often since they sometimes
paint to their own layers.

These metrics are high-level and not super actionable on their own;
they are mainly intended to catch regressions.

Change-Id: Ie90f5db94ffab163aaf475c19ea678276db3b308
Bug: 966237
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1626169
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Auto-Submit: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Reviewed-by: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665003}

chrome/browser/ui/views/tabs/tab_icon.cc

@@ -4,7 +4,10 @@
 
 #include "chrome/browser/ui/views/tabs/tab_icon.h"
 
+#include "base/metrics/histogram_macros.h"
 #include "base/time/default_tick_clock.h"
+#include "base/timer/elapsed_timer.h"
+#include "base/trace_event/trace_event.h"
 #include "cc/paint/paint_flags.h"
 #include "chrome/browser/favicon/favicon_utils.h"
 #include "chrome/browser/themes/theme_properties.h"
@@ -167,6 +170,9 @@ void TabIcon::SetBackgroundColor(SkColor bg_color) {
 }
 
 void TabIcon::OnPaint(gfx::Canvas* canvas) {
+  // This is used to log to UMA. NO EARLY RETURNS!
+  base::ElapsedTimer paint_timer;
+
   // Compute the bounds adjusted for the hiding fraction.
   gfx::Rect contents_bounds = GetContentsBounds();
 
@@ -183,19 +189,23 @@ void TabIcon::OnPaint(gfx::Canvas* canvas) {
   // The old animation replaces the favicon and should early-abort.
   if (!use_new_loading_animation_ && ShowingLoadingAnimation()) {
     PaintLoadingAnimation(canvas, icon_bounds);
-    return;
-  }
-
-  // Don't paint the attention indicator during the loading animation.
-  if (!ShowingLoadingAnimation() && ShowingAttentionIndicator() &&
-      !should_display_crashed_favicon_) {
-    PaintAttentionIndicatorAndIcon(canvas, GetIconToPaint(), icon_bounds);
   } else {
-    MaybePaintFavicon(canvas, GetIconToPaint(), icon_bounds);
+    // Don't paint the attention indicator during the loading animation.
+    if (!ShowingLoadingAnimation() && ShowingAttentionIndicator() &&
+        !should_display_crashed_favicon_) {
+      PaintAttentionIndicatorAndIcon(canvas, GetIconToPaint(), icon_bounds);
+    } else {
+      MaybePaintFavicon(canvas, GetIconToPaint(), icon_bounds);
+    }
+
+    if (ShowingLoadingAnimation())
+      PaintLoadingAnimation(canvas, icon_bounds);
   }
 
-  if (ShowingLoadingAnimation())
-    PaintLoadingAnimation(canvas, icon_bounds);
+  UMA_HISTOGRAM_CUSTOM_MICROSECONDS_TIMES(
+      "TabStrip.Tab.Icon.PaintDuration", paint_timer.Elapsed(),
+      base::TimeDelta::FromMicroseconds(1),
+      base::TimeDelta::FromMicroseconds(10000), 50);
 }
 
 void TabIcon::OnThemeChanged() {
@@ -216,6 +226,8 @@ void TabIcon::AnimationEnded(const gfx::Animation* animation) {
 void TabIcon::PaintAttentionIndicatorAndIcon(gfx::Canvas* canvas,
                                              const gfx::ImageSkia& icon,
                                              const gfx::Rect& bounds) {
+  TRACE_EVENT0("views", "TabIcon::PaintAttentionIndicatorAndIcon");
+
   gfx::Point circle_center(
       bounds.x() + (base::i18n::IsRTL() ? 0 : gfx::kFaviconSize),
       bounds.y() + gfx::kFaviconSize);
@@ -247,6 +259,8 @@ void TabIcon::PaintAttentionIndicatorAndIcon(gfx::Canvas* canvas,
 }
 
 void TabIcon::PaintLoadingAnimation(gfx::Canvas* canvas, gfx::Rect bounds) {
+  TRACE_EVENT0("views", "TabIcon::PaintLoadingAnimation");
+
   const ui::ThemeProvider* tp = GetThemeProvider();
   base::Optional<SkScalar> stroke_width;
   if (use_new_loading_animation_)
@@ -287,6 +301,8 @@ const gfx::ImageSkia& TabIcon::GetIconToPaint() {
 void TabIcon::MaybePaintFavicon(gfx::Canvas* canvas,
                                 const gfx::ImageSkia& icon,
                                 const gfx::Rect& bounds) {
+  TRACE_EVENT0("views", "TabIcon::MaybePaintFavicon");
+
   if (icon.isNull())
     return;
 

chrome/browser/ui/views/tabs/tab_strip.cc

@@ -23,6 +23,7 @@
 #include "base/no_destructor.h"
 #include "base/stl_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/timer/elapsed_timer.h"
 #include "build/build_config.h"
 #include "chrome/browser/defaults.h"
 #include "chrome/browser/themes/theme_properties.h"
@@ -1829,6 +1830,9 @@ bool TabStrip::OnMouseWheel(const ui::MouseWheelEvent& event) {
 }
 
 void TabStrip::PaintChildren(const views::PaintInfo& paint_info) {
+  // This is used to log to UMA. NO EARLY RETURNS!
+  base::ElapsedTimer paint_timer;
+
   // The view order doesn't match the paint order (tabs_ contains the tab
   // ordering). Additionally we need to paint the tabs that are closing in
   // |tabs_closing_map_|.
@@ -1918,6 +1922,11 @@ void TabStrip::PaintChildren(const views::PaintInfo& paint_info) {
   // If the active tab is being dragged, it goes last.
   if (active_tab && is_dragging)
     active_tab->Paint(paint_info);
+
+  UMA_HISTOGRAM_CUSTOM_MICROSECONDS_TIMES(
+      "TabStrip.PaintChildrenDuration", paint_timer.Elapsed(),
+      base::TimeDelta::FromMicroseconds(1),
+      base::TimeDelta::FromMicroseconds(10000), 50);
 }
 
 const char* TabStrip::GetClassName() const {

tools/metrics/histograms/histograms.xml

@@ -131859,6 +131859,33 @@ should be kept until we use this API.  -->
   </summary>
 </histogram>
 
+<histogram name="TabStrip.PaintChildrenDuration" units="microseconds"
+    expires_after="M80">
+  <owner>collinbaker@chromium.org</owner>
+  <owner>chrome-desktop-ui-sea@google.com</owner>
+  <summary>
+    Total time spent in each call of TabStrip::PaintChildren(). This comprises
+    the paint time for all parts of the TabStrip that do not paint to their own
+    layers. This is recorded at the end of TabStrip::PaintChildren(), when all
+    child views are finished painting.
+
+    As of writing (May 17, 2019), this always includes the tab backgrounds,
+    strokes, labels, close buttons. The tab icons and new tab button sometimes
+    paint to their own layer; in frames where this is so, their times won't be
+    included here.
+  </summary>
+</histogram>
+
+<histogram name="TabStrip.Tab.Icon.PaintDuration" units="microseconds"
+    expires_after="M80">
+  <owner>collinbaker@chromium.org</owner>
+  <owner>chrome-desktop-ui-sea@google.com</owner>
+  <summary>
+    Time spent painting a tab icon. This includes a page's favicon and loading
+    animation (when loading). This is recorded at the end of TabIcon::OnPaint().
+  </summary>
+</histogram>
+
 <histogram name="TabStrip.TabCountOnPageLoad" units="tabs"
     expires_after="2020-01-01">
   <owner>yusufo@chromium.org</owner>