Refactor budget computation to be more tuneable.

chrome/browser/push_messaging/push_messaging_browsertest.cc

 // Copyright 2014 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 <stddef.h>
 #include <stdint.h>
 
 #include <map>
 #include <string>
 
@@ skipping 1199 matching lines @@
   ASSERT_EQ("true - is controlled", script_result);
 
   notification_manager()->CancelAll();
   ASSERT_EQ(0u, notification_manager()->GetNotificationCount());
 
   // We'll need to specify the web_contents in which to eval script, since we're
   // going to run script in a background tab.
   content::WebContents* web_contents =
       GetBrowser()->tab_strip_model()->GetActiveWebContents();
 
-  // Set the site engagement score for the site. Setting it to 4 means it should
-  // have enough budget for two non-shown notification, which cost 2 each.
-  SetSiteEngagementScore(web_contents->GetURL(), 4.0);
+  // Set the site engagement score for the site. Setting it to 10 means it
+  // should have a budget of 4, enough for two non-shown notification, which
+  // cost 2 each.

[Peter Beverloo, 2017/01/12 14:40:04]

I'd love to be able to use constants for this. Can we use something like
BudgetFoo::GetMaxSilentPushCost() or something like that?

(Doing this later is fine.)

[harkness, 2017/01/12 17:44:15]

I think that's a great idea, and I will absolutely do it later.

+  SetSiteEngagementScore(web_contents->GetURL(), 10.0);
 
   // If the site is visible in an active tab, we should not force a notification
   // to be shown. Try it twice, since we allow one mistake per 10 push events.
   gcm::IncomingMessage message;
   message.sender_id = GetTestApplicationServerKey();
   message.decrypted = true;
   for (int n = 0; n < 2; n++) {
     message.raw_data = "testdata";
     SendMessageAndWaitUntilHandled(app_identifier, message);
     ASSERT_TRUE(RunScript("resultQueue.pop()", &script_result));
@@ skipping 887 matching lines @@
   ASSERT_NO_FATAL_FAILURE(SubscribeSuccessfully());
   ASSERT_FALSE(background_mode_manager->IsBackgroundModeActive());
 
   // After dropping the last subscription background mode is still inactive.
   std::string script_result;
   ASSERT_TRUE(RunScript("unsubscribePush()", &script_result));
   EXPECT_EQ("unsubscribe result: true", script_result);
   ASSERT_FALSE(background_mode_manager->IsBackgroundModeActive());
 }
 #endif  // BUILDFLAG(ENABLE_BACKGROUND) && !defined(OS_CHROMEOS)