Adds a perf test for initializing and painting a views::LabelButton

ui/views/controls/button/label_button_perftest.cc

Index: ui/views/controls/button/label_button_perftest.cc
diff --git a/ui/views/controls/button/label_button_perftest.cc b/ui/views/controls/button/label_button_perftest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..186ab997e6a2a167f19cd70370a46bf69297bb28
--- /dev/null
+++ b/ui/views/controls/button/label_button_perftest.cc
@@ -0,0 +1,147 @@
+// Copyright 2015 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 "ui/views/controls/button/label_button.h"
+
+#include "base/strings/utf_string_conversions.h"
+#include "base/test/perf_time_logger.h"
+#include "cc/playback/display_item_list.h"
+#include "cc/playback/display_item_list_settings.h"
+#include "ui/compositor/paint_context.h"
+#include "ui/views/test/widget_test.h"
+
+namespace views {
+namespace {
+
+const int kWarmupIterations = 20;
+const int kScaleFactor = 2.0f;  // Test HiDPI.
+
+class LabelButtonPerfTest : public test::WidgetTest {
+ public:
+  LabelButtonPerfTest() {}
+
+  // Body of the test after a button has been created. Goal is to simulate the
+  // impact of adding one additional button on the time to first paint a dialog.
+  void PostCreateTestBody(const ui::PaintContext& paint_context, View* view) {
+    view->SizeToPreferredSize();
+    widget_->GetContentsView()->AddChildView(view);
+    widget_->GetContentsView()->Layout();
+    // Paint into a new canvas. This gets adopted by the View's PaintCache to
+    // emulate a "first" paint scenario. Paints the root view, so that the
+    // PaintContext can be reused.
+    widget_->GetRootView()->Paint(paint_context);
+  }
+
+  void RunViewInitPaintTest(const char* test_name,
+                            const base::Callback<View*()>& factory,
+                            int perf_test_iterations) {
+    // Create a template view to determine size and ensure resources are loaded
+    // for the given scale factor.
+    gfx::Rect canvas_rect;
+    {
+      const gfx::Rect template_rect(100, 100);
+      scoped_refptr<cc::DisplayItemList> list = cc::DisplayItemList::Create(
+          template_rect, cc::DisplayItemListSettings());
+      ui::PaintContext paint_context(list.get(), kScaleFactor, template_rect,
+                                     template_rect);
+      scoped_ptr<View> template_view(factory.Run());
+      PostCreateTestBody(paint_context, template_view.get());
+      canvas_rect = template_view->bounds();
+    }
+
+    // Sanity check to ensure something is happening.
+    EXPECT_LT(10, canvas_rect.width());
+    EXPECT_LT(10, canvas_rect.height());
+
+    // Repaint with the same PaintContext each time.
+    scoped_refptr<cc::DisplayItemList> list =
+        cc::DisplayItemList::Create(canvas_rect, cc::DisplayItemListSettings());
+    ui::PaintContext paint_context(list.get(), kScaleFactor, canvas_rect,
+                                   canvas_rect);
+
+    for (int iteration = 0; iteration < kWarmupIterations; ++iteration) {
+      scoped_ptr<View> view(factory.Run());
+      PostCreateTestBody(paint_context, view.get());
+    }
+
+    base::PerfTimeLogger timer(test_name);
+    for (int iteration = 0; iteration < perf_test_iterations; ++iteration) {
+      scoped_ptr<View> view(factory.Run());
+      PostCreateTestBody(paint_context, view.get());
+      // scoped_ptr destructor removes the button from the hierarchy.
+    }
+    // PerfTimeLogger destructor logs duration.
+  }
+
+  // testing::Test:
+  void SetUp() override {
+    ViewsTestBase::SetUp();
+    // Some initialization (e.g. for theming) does not occur until a view is
+    // actually added to a widget. Create a widget for that, but don't ever show
+    // it nor paint it.
+    widget_ = CreateTopLevelPlatformWidget();
+    widget_->SetSize(gfx::Size(200, 200));
+    widget_->Show();
+  }
+
+  void TearDown() override {
+    widget_->CloseNow();
+    ViewsTestBase::TearDown();
+  }
+
+ protected:
+  Widget* widget_ = nullptr;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(LabelButtonPerfTest);
+};
+
+// Factory functions for the test. Try to mimic the manner by which Views are
+// are typically created in client code.
+View* CreateTextbutton(const base::string16& text) {
+  return new LabelButton(nullptr, text);
+}
+
+View* CreateButton(const base::string16& text) {
+  LabelButton* button = new LabelButton(nullptr, text);
+  button->SetStyle(Button::STYLE_BUTTON);
+  return button;
+}
+
+}  // namespace
+
+// Performance tests for initializing a LabelButton, adding it to a View
+// hierarchy, then performing a "first" paint. Ballpark figures are given for
+// the duration of a single iteration on a z620 running Linux.
+
+// Test STYLE_TEXTBUTTON with no text. Ballpark: 1ms debug 0.3ms release.
+TEST_F(LabelButtonPerfTest, InitAndPaintTextbuttonNoText) {
+  RunViewInitPaintTest("views_label_button_text_button_no_text_1000",
+                       base::Bind(&CreateTextbutton, base::string16()),
+                       1000);
+}
+
+// Test STYLE_TEXTBUTTON with the label "abc". Ballpark: 8ms debug, 7ms release.
+TEST_F(LabelButtonPerfTest, InitAndPaintTextbuttonAbcText) {
+  RunViewInitPaintTest(
+      "views_label_button_text_button_abc_text_100",
+      base::Bind(&CreateTextbutton, base::ASCIIToUTF16("abc")),
+      100);
+}
+
+// Test STYLE_BUTTON with no text. Ballpark: 2.5ms debug 1ms release.
+TEST_F(LabelButtonPerfTest, InitAndPaintButtonNoText) {
+  RunViewInitPaintTest("views_label_button_button_no_text_1000",
+                       base::Bind(&CreateButton, base::string16()),
+                       1000);
+}
+
+// Test STYLE_BUTTON with the label "abc". Ballpark: 12ms debug, 9ms release.
+TEST_F(LabelButtonPerfTest, InitAndPaintButtonAbcText) {
+  RunViewInitPaintTest("views_label_button_button_abc_text_100",
+                       base::Bind(&CreateButton, base::ASCIIToUTF16("abc")),
+                       100);
+}
+
+}  // namespace views