Update comments in InstallableManager.

chrome/browser/installable/installable_manager.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/installable/installable_manager.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "chrome/browser/manifest/manifest_icon_downloader.h"
 #include "chrome/browser/manifest/manifest_icon_selector.h"
 #include "chrome/browser/profiles/profile.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/navigation_handle.h"
 #include "content/public/browser/service_worker_context.h"
 #include "content/public/browser/storage_partition.h"
 #include "third_party/WebKit/public/platform/WebDisplayMode.h"
 
 namespace {
 
 const char kPngExtension[] = ".png";
 
 // This constant is the icon size on Android (48dp) multiplied by the scale
 // factor of a Nexus 5 device (3x). For mobile and desktop platforms, a 144px
-// icon is an approximate, appropriate lower bound.
+// icon is an approximate, appropriate lower bound. It is currently documented
+// as the minimum requirement for triggering banners on several web
+// documentation pages, e.g.
+// https://developers.google.com/web/fundamentals/engage-and-retain/app-install-banners/,

[dominickn, 2016/10/27 00:26:36]

The links here are unnecessary (and overflow the 80 character width limit).
Please remove them. The only addition that's really necessary is the sentence.

"It is the currently advertised minimum icon size for triggering banners."

[F, 2016/10/27 17:49:24]

Done.

+// https://developers.google.com/web/updates/2015/03/increasing-engagement-with-app-install-banners-in-chrome-for-android,
+// https://googlechrome.github.io/samples/app-install-banner/
 // TODO(dominickn): consolidate with minimum_icon_size_in_dp across platforms.
 const int kIconMinimumSizeInPx = 144;
 
 // Returns true if |manifest| specifies a PNG icon >= 144x144px (or size "any").
 bool DoesManifestContainRequiredIcon(const content::Manifest& manifest) {
   for (const auto& icon : manifest.icons) {
     // The type field is optional. If it isn't present, fall back on checking
     // the src extension, and allow the icon if the extension ends with png.
     if (!base::EqualsASCII(icon.type, "image/png") &&
         !(icon.type.empty() && base::EndsWith(
@@ skipping 399 matching lines @@
   return manifest_->url;
 }
 
 const content::Manifest& InstallableManager::manifest() const {
   return manifest_->manifest;
 }
 
 bool InstallableManager::is_installable() const {
   return installable_->installable;
 }