Refactor budget computation to be more tuneable.

third_party/WebKit/LayoutTests/http/tests/budget/budget-service-mock.js

 /**
  * Mock implementation of the budget service.
  */
 
 "use strict";
 
 const TEST_BUDGET_COST = 1.2;
-const TEST_BUDGET_AT = 2.3;
+const TEST_BUDGET_AT = 2;
 const TEST_BUDGET_TIME = new Date().getTime();
 
 let budgetServiceMock = loadMojoModules(
     'budgetServiceMock',
     ['third_party/WebKit/public/platform/modules/budget_service/budget_service.mojom',
      'mojo/public/js/bindings'
     ]).then(mojo => {
   const [budgetService, bindings] = mojo.modules;
 
   class BudgetServiceMock {
@@ skipping 64 matching lines @@
       return Promise.resolve({ error_type: this.error_, budget: this.budget_ });
     }
 
     // This provides an implementation for the Mojo serivce reserve call.
     reserve() {
       return Promise.resolve({ error_type: this.error_, success: this.success_ });
     }
   }
   return new BudgetServiceMock(mojo.interfaces);
 });