Backfill some UI tests.

chrome/browser/ui/views/validation_message_bubble_view_unittest.cc

+// Copyright 2017 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/views/validation_message_bubble_view.h"
+
+#include "base/command_line.h"
+#include "base/strings/utf_string_conversions.h"
+#include "chrome/test/base/chrome_render_view_host_test_harness.h"
+#include "content/public/browser/web_contents.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/display/display_switches.h"
+#include "ui/views/layout/layout_provider.h"
+#include "ui/views/test/scoped_views_test_helper.h"
+#include "ui/views/test/test_views_delegate.h"
+
+namespace {
+constexpr float kScaleFactor = 1.5;
+constexpr gfx::Rect kInitialAnchorRect = gfx::Rect(10, 20, 30, 40);
+}  // namespace
+
+class ValidationMessageBubbleViewTest : public ChromeRenderViewHostTestHarness {
+ public:
+  ValidationMessageBubbleViewTest() = default;
+
+  void SetUp() override {
+    // Append the switch before any other setup.
+    base::CommandLine::ForCurrentProcess()->AppendSwitchASCII(
+        switches::kForceDeviceScaleFactor, std::to_string(kScaleFactor));

[sky, 2017/05/07 22:44:23]

Wow, I didn't realize std got a std::to_string function in c++11. Nice!

+
+    ChromeRenderViewHostTestHarness::SetUp();
+
+    // Owned by the parent view.

[sky, 2017/05/07 22:44:23]

This comment is mildly confusing given there is no parent here, and actually
ValidationMessageBubbleView manages it's own lifetime, which is handled in
DialogDelegateView.

[Bret, 2017/05/09 23:44:42]

You're right. I thought the NativeView shenanigans were required because that
was the owner, but I guess not. I deleted the comment since the owner is clearly
not the test anyway.

+    bubble_ = new ValidationMessageBubbleView(
+        web_contents(), kInitialAnchorRect, base::ASCIIToUTF16("MAIN TEXT"),
+        base::ASCIIToUTF16("SUB TEXT"));
+  }
+
+  ValidationMessageBubbleView& bubble() { return *bubble_; }
+
+ private:
+  views::LayoutProvider provider_;  // Creates a singleton.
+  ValidationMessageBubbleView* bubble_;
+
+  DISALLOW_COPY_AND_ASSIGN(ValidationMessageBubbleViewTest);
+};
+
+TEST_F(ValidationMessageBubbleViewTest,
+       AnchorRectIsCorrectForDeviceScaleFactor) {
+  constexpr float inverse_scale_factor = 1 / kScaleFactor;
+  EXPECT_EQ(gfx::ScaleToEnclosingRect(kInitialAnchorRect, inverse_scale_factor),
+            bubble().anchor_rect());
+
+  const gfx::Rect updated_anchor_rect(66, 99, 44, 33);

[sky, 2017/05/07 22:44:23]

Add comment as to where these values come from.

[Bret, 2017/05/09 23:44:42]

They're just arbitrary test values. I made them slightly less goofy so hopefully
that's clearer.

+  bubble().SetPositionRelativeToAnchor(
+      web_contents()->GetRenderWidgetHostView()->GetRenderWidgetHost(),
+      updated_anchor_rect);
+  EXPECT_EQ(
+      gfx::ScaleToEnclosingRect(updated_anchor_rect, inverse_scale_factor),
+      bubble().anchor_rect());
+}