Expose a WasLaunchedRecently method using the app banner content setting.

chrome/browser/banners/app_banner_settings_helper.h

Index: chrome/browser/banners/app_banner_settings_helper.h
diff --git a/chrome/browser/banners/app_banner_settings_helper.h b/chrome/browser/banners/app_banner_settings_helper.h
index 42dfdbb198a1a39394a2b2159f6afb02fbf8a928..9ba0214051728ad1e9c88dd98d6fc401efcf729a 100644
--- a/chrome/browser/banners/app_banner_settings_helper.h
+++ b/chrome/browser/banners/app_banner_settings_helper.h
@@ -130,6 +130,14 @@ class AppBannerSettingsHelper {
       const std::string& package_name_or_start_url,
       base::Time time);
 
+  // Returns true if any site under |origin| was launched from homescreen in the
+  // last ten days. This allows services outside app banners to utilise the
+  // content setting that ensures app banners are not shown for sites which ave
+  // already been added to homescreen.
+  static bool WasLaunchedRecently(content::WebContents* web_contents,

[benwells, 2016/07/28 07:47:01]

Its kind of weird that ImportantSites would depend on code in banners/ to see if
something had been launched from the homescreen.

Something to clean up in future CLs.

[dominickn, 2016/07/29 00:34:08]

Yeah, this is definitely something I want to tidy up. It's a mess with the Java
side / native side split. It's unfortunate that the one consistent marker of
homescreen-ness across both is the freshness of this content setting event.

+                                  const GURL& origin_url,
+                                  base::Time now);
+
   // Set the engagement weights assigned to direct and indirect navigations.
   static void SetEngagementWeights(double direct_engagement,
                                    double indirect_engagement);