Update comments in InstallableManager.

chrome/browser/installable/installable_manager.cc

Index: chrome/browser/installable/installable_manager.cc
diff --git a/chrome/browser/installable/installable_manager.cc b/chrome/browser/installable/installable_manager.cc
index f58783fea652ac86a1891b1e766f4b41b8de54e2..7b35bfb667740e3272a6595f552e1e0a0f31afdd 100644
--- a/chrome/browser/installable/installable_manager.cc
+++ b/chrome/browser/installable/installable_manager.cc
@@ -22,7 +22,12 @@ 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;