Log messages regarding why app banners aren't displayed to the console

chrome/browser/banners/app_banner_manager.cc

 // Copyright 2015 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.h"
 
 #include "base/metrics/field_trial.h"
 #include "chrome/browser/banners/app_banner_data_fetcher.h"
+#include "chrome/browser/banners/app_banner_debug_log.h"
 #include "chrome/browser/banners/app_banner_settings_helper.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/frame_navigate_params.h"
 #include "net/base/load_flags.h"
 #include "ui/gfx/screen.h"
 
 namespace {
 bool gDisableSecureCheckForTesting = false;
@@ skipping 23 matching lines @@
   if (render_frame_host->GetParent())
     return;
 
   if (data_fetcher_.get() && data_fetcher_->is_active() &&
       URLsAreForTheSamePage(data_fetcher_->validated_url(), validated_url)) {
     return;
   }
 
   // A secure scheme is required to show banners, so exit early if we see the
   // URL is invalid.
-  if (!validated_url.SchemeIsSecure() && !gDisableSecureCheckForTesting)
+  if (!validated_url.SchemeIsSecure() && !gDisableSecureCheckForTesting) {
+    SendDebugMessage(web_contents(),
+                     "not shown: page not served over secure scheme");

[benwells, 2015/05/11 08:08:40]

FYI this is about to go out of date. To match the next version say something
like 'from a secure origin.'

[dominickn (DO NOT USE), 2015/05/12 07:41:31]

Done.

     return;
+  }
 
   // Kick off the data retrieval pipeline.
   data_fetcher_ = CreateAppBannerDataFetcher(weak_factory_.GetWeakPtr(),
                                              ideal_icon_size_);
   data_fetcher_->Start(validated_url);
 }
 
 
 bool AppBannerManager::HandleNonWebApp(const std::string& platform,
                                        const GURL& url,
@@ skipping 27 matching lines @@
 
 void AppBannerManager::DisableSecureSchemeCheckForTesting() {
   gDisableSecureCheckForTesting = true;
 }
 
 bool AppBannerManager::IsEnabled() {
   return base::FieldTrialList::FindFullName("AppBanners") == "Enabled";
 }
 
 }  // namespace banners