Make all quota-exceeding messages in the storage API explain what the failure

chrome/browser/extensions/settings/settings_storage_quota_enforcer.cc

 // Copyright (c) 2012 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/extensions/settings/settings_storage_quota_enforcer.h"
 
 #include "base/bind.h"
 #include "base/json/json_writer.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "chrome/common/extensions/api/extension_api.h"
+#include "chrome/common/extensions/extension_error_utils.h"
 
 namespace extensions {
 
 namespace {
 
-const char* kExceededQuotaErrorMessage = "Quota exceeded";
+const char* kQuotaExceededError = "* quota exceeded.";
 
 // Resources there are a quota for.
 enum Resource {
   QUOTA_BYTES,
   QUOTA_BYTES_PER_ITEM,
   MAX_ITEMS
 };
 
 // Allocates a setting in a record of total and per-setting usage.
 void Allocate(
@@ skipping 18 matching lines @@
 void Free(
     size_t* used_total,
     std::map<std::string, size_t>* used_per_setting,
     const std::string& key) {
   *used_total -= (*used_per_setting)[key];
   used_per_setting->erase(key);
 }
 
 // Returns an error result and logs the quota exceeded to UMA.
 ValueStore::WriteResult QuotaExceededFor(Resource resource) {
+  std::string name;
   switch (resource) {
     case QUOTA_BYTES:
+      name = "QUOTA_BYTES";
       UMA_HISTOGRAM_COUNTS_100(
           "Extensions.SettingsQuotaExceeded.TotalBytes", 1);
       break;
     case QUOTA_BYTES_PER_ITEM:
+      name = "QUOTA_BYTES_PER_ITEM";
       UMA_HISTOGRAM_COUNTS_100(
           "Extensions.SettingsQuotaExceeded.BytesPerSetting", 1);
       break;
     case MAX_ITEMS:
+      name = "MAX_ITEMS";
       UMA_HISTOGRAM_COUNTS_100(
           "Extensions.SettingsQuotaExceeded.KeyCount", 1);
       break;
     default:
       NOTREACHED();
   }
-  return ValueStore::MakeWriteResult(kExceededQuotaErrorMessage);
+  return ValueStore::MakeWriteResult(
+      ExtensionErrorUtils::FormatErrorMessage(kQuotaExceededError, name));
 }
 
 }  // namespace
 
 SettingsStorageQuotaEnforcer::SettingsStorageQuotaEnforcer(
     const Limits& limits, ValueStore* delegate)
     : limits_(limits), delegate_(delegate), used_total_(0) {
   ReadResult maybe_settings = delegate_->Get();
   if (maybe_settings->HasError()) {
     LOG(WARNING) << "Failed to get initial settings for quota: " <<
@@ skipping 136 matching lines @@
     return result.Pass();
   }
 
   while (!used_per_setting_.empty()) {
     Free(&used_total_, &used_per_setting_, used_per_setting_.begin()->first);
   }
   return result.Pass();
 }
 
 }  // namespace extensions