DevTools: account for the display scale factor while validating manifest under emulation.

chrome/browser/banners/app_banner_manager_emulation.cc

+// Copyright 2016 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/banners/app_banner_manager_emulation.h"
+
+#include "base/command_line.h"
+#include "build/build_config.h"
+#include "chrome/browser/banners/app_banner_data_fetcher_desktop.h"
+#include "ui/display/screen.h"
+
+namespace {
+
+// We need to provide web developers with the guidance on the minimum icon
+// size they should list in the manifest. Since the size depends on the
+// device, we pick the baseline being a Nexus 5X-alike device.
+// We make it clear in the 'add to home screen' emulation UI that the

[dominickn, 2016/05/06 18:29:47]

Nit: It would be nice if it was also stated in the emulation UI that this won't
properly emulate a native app banner, just a web app banner (since the code to
query the Play Store for native data is Android-only)

[pfeldman, 2016/05/06 18:40:01]

We'll get this messaging aligned with Jake.

+// size does not correspond to the currently emulated device, but rather is
+// a generic baseline.
+int kMinimumIconSize = 192;

[dominickn, 2016/05/06 18:29:47]

I think this should be 144px - that has been the advertised minimum size for
some time; for a Nexus 5X, I believe we have 48dp (homescreen icon size) * 3
(scale factor) = 144px.

Minor nit: const int?

[pfeldman, 2016/05/06 18:40:01]

Done.

+
+}  // anonymous namespace
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(banners::AppBannerManagerEmulation);
+
+namespace banners {
+
+AppBannerDataFetcher* AppBannerManagerEmulation::CreateAppBannerDataFetcher(
+    base::WeakPtr<AppBannerDataFetcher::Delegate> weak_delegate,
+    bool is_debug_mode) {
+

[dominickn, 2016/05/06 18:29:46]

Nit: add a comment along the lines of "Divide by the current screen density as
the data fetcher will multiply it back in when trying to fetch an appropriate
icon".

[pfeldman, 2016/05/06 18:40:01]

Done.

+  int size = kMinimumIconSize / display::Screen::GetScreen()->
+      GetPrimaryDisplay().device_scale_factor();
+
+  return new AppBannerDataFetcherDesktop(web_contents(), weak_delegate,
+                                         size, size, true);

[dominickn, 2016/05/06 18:29:46]

Nit: pass through is_debug_mode for consistency.

[pfeldman, 2016/05/06 18:40:01]

Done.

+}
+
+AppBannerManagerEmulation::AppBannerManagerEmulation(
+    content::WebContents* web_contents)
+    : AppBannerManager(web_contents) {
+}
+
+}  // namespace banners