[Extensions Metrics] Fix integer division error

There was an integer division error in reporting one of our percentages.
Fix it, and add a test to cover the case.

Bug: None
Change-Id: Ibc1993852644c86fdfe356862cbb8e5bc51644dd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2265420Reviewed-by: Caroline Rising <corising@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#782684}

chrome/browser/ui/toolbar/toolbar_actions_model.cc

@@ -519,11 +519,11 @@ void ToolbarActionsModel::InitializeActionList() {
     if (!profile_->IsOffTheRecord() && !action_ids_.empty()) {
       base::UmaHistogramCounts100("Extensions.Toolbar.PinnedExtensionCount2",
                                   pinned_action_ids_.size());
-      double percentage_double =
-          pinned_action_ids_.size() / action_ids_.size() * 100.0;
+      double percentage_double = double{pinned_action_ids_.size()} /
+                                 double{action_ids_.size()} * 100.0;
       int percentage = int{percentage_double};
       base::UmaHistogramPercentage(
-          "Extensions.Toolbar.PinnedExtensionPercentage2", percentage);
+          "Extensions.Toolbar.PinnedExtensionPercentage3", percentage);
     }
   }
 }

chrome/browser/ui/toolbar/toolbar_actions_model_browsertest.cc

+// Copyright 2020 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.
+
+#include "chrome/browser/ui/toolbar/toolbar_actions_model.h"
+
+#include "base/test/metrics/histogram_tester.h"
+#include "base/test/scoped_feature_list.h"
+#include "chrome/browser/extensions/extension_browsertest.h"
+#include "chrome/browser/ui/ui_features.h"
+#include "content/public/test/browser_test.h"
+
+class ToolbarActionsModelBrowserTest : public extensions::ExtensionBrowserTest {
+ public:
+  ToolbarActionsModelBrowserTest() {
+    scoped_feature_list_.InitAndEnableFeature(features::kExtensionsToolbarMenu);
+  }
+  ~ToolbarActionsModelBrowserTest() override = default;
+
+  base::HistogramTester* histogram_tester() { return &histogram_tester_; }
+
+ private:
+  base::test::ScopedFeatureList scoped_feature_list_;
+  base::HistogramTester histogram_tester_;
+};
+
+IN_PROC_BROWSER_TEST_F(ToolbarActionsModelBrowserTest, PRE_PinnedStateMetrics) {
+  const extensions::Extension* extension1 =
+      LoadExtension(test_data_dir_.AppendASCII("simple_with_file"));
+  ASSERT_TRUE(extension1);
+
+  const extensions::Extension* extension2 =
+      LoadExtension(test_data_dir_.AppendASCII("simple_with_icon"));
+  ASSERT_TRUE(extension2);
+
+  ToolbarActionsModel* model = ToolbarActionsModel::Get(profile());
+  EXPECT_EQ(2u, model->action_ids().size());
+
+  EXPECT_FALSE(model->IsActionPinned(extension1->id()));
+  EXPECT_FALSE(model->IsActionPinned(extension2->id()));
+  model->SetActionVisibility(extension1->id(), true);
+  EXPECT_TRUE(model->IsActionPinned(extension1->id()));
+  EXPECT_FALSE(model->IsActionPinned(extension2->id()));
+}
+
+IN_PROC_BROWSER_TEST_F(ToolbarActionsModelBrowserTest, PinnedStateMetrics) {
+  ToolbarActionsModel* model = ToolbarActionsModel::Get(profile());
+  EXPECT_EQ(2u, model->action_ids().size());
+  EXPECT_EQ(1u, model->pinned_action_ids().size());
+
+  histogram_tester()->ExpectUniqueSample(
+      "Extensions.Toolbar.PinnedExtensionPercentage3", 50, 1);
+  histogram_tester()->ExpectUniqueSample(
+      "Extensions.Toolbar.PinnedExtensionCount2", 1, 1);
+}

chrome/test/BUILD.gn

@@ -1292,6 +1292,7 @@ if (!is_android) {
       "../browser/ui/thumbnails/thumbnail_tab_helper_browsertest.cc",
       "../browser/ui/toolbar/browser_actions_bar_browsertest.cc",
       "../browser/ui/toolbar/browser_actions_bar_browsertest.h",
+      "../browser/ui/toolbar/toolbar_actions_model_browsertest.cc",
       "../browser/ui/update_chrome_dialog_browsertest.cc",
       "../browser/ui/views/apps/app_info_dialog/app_info_dialog_views_browsertest.cc",
       "../browser/ui/views/bookmarks/bookmark_bar_view_browsertest.cc",

tools/metrics/histograms/histograms.xml

@@ -59089,6 +59089,21 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 
 <histogram name="Extensions.Toolbar.PinnedExtensionPercentage2" units="%"
     expires_after="2021-06-30">
+  <obsolete>
+    Replaced by Extensions.Toolbar.PinnedExtensionPercentage3 in 2020/05.
+  </obsolete>
+  <owner>rdevlin.cronin@chromium.org</owner>
+  <owner>extensions-core@chromium.org</owner>
+  <summary>
+    The percentage of extensions that the user has pinned to the toolbar (i.e.,
+    this will be 100 if the user has every extension pinned). Recorded once per
+    profile during initialization if the user has at least one extension with an
+    action in the toolbar.
+  </summary>
+</histogram>
+
+<histogram name="Extensions.Toolbar.PinnedExtensionPercentage3" units="%"
+    expires_after="2021-06-30">
   <owner>rdevlin.cronin@chromium.org</owner>
   <owner>extensions-core@chromium.org</owner>
   <summary>