Extension Storage API: expose storage quota information to extensions, via:

chrome/browser/extensions/settings/settings_frontend.cc

Index: chrome/browser/extensions/settings/settings_frontend.cc
diff --git a/chrome/browser/extensions/settings/settings_frontend.cc b/chrome/browser/extensions/settings/settings_frontend.cc
index 8d7d914cff0d9cfaa6eddd268a89a3dc7f529eb5..f6ba2bb14b12a9fb042e9273e25d8f430cfbd3d9 100644
--- a/chrome/browser/extensions/settings/settings_frontend.cc
+++ b/chrome/browser/extensions/settings/settings_frontend.cc
@@ -23,29 +23,6 @@ namespace extensions {
 
 namespace {
 
-const SettingsStorageQuotaEnforcer::Limits kSyncQuota = {
-  // 100K should be enough for simple use, but this can be increased as demand
-  // increases.
-  100 * 1024,
-
-  // Sync supports 5k per settings, so be a bit more restrictive than that.
-  2048,
-
-  // Keep low for sync.
-  512
-};
-
-const SettingsStorageQuotaEnforcer::Limits kLocalQuota = {
-  // Same as localStorage (5MB).
-  5 * 1000 * 1024,
-
-  // No need to be restrictive per key here.
-  UINT_MAX,
-
-  // Ditto.
-  UINT_MAX
-};
-
 // Settings change Observer which forwards changes on to the extension
 // processes for |profile| and its incognito partner if it exists.
 class DefaultObserver : public SettingsObserver {
@@ -111,6 +88,33 @@ void CallbackWithUnlimitedStorage(
 
 }  // namespace
 
+// The values in kSyncQuota and kLocalQuota must match those in
+// chrome/common/extensions/api/storage.json
+
+// static
+const SettingsStorageQuotaEnforcer::Limits SettingsFrontend::kSyncQuota = {
+  // 100K should be enough for simple use, but this can be increased as demand
+  // increases.
+  100 * 1024,
+
+  // Sync supports 5k per settings, so be a bit more restrictive than that.
+  2048,
+
+  // Keep low for sync.
+  512
+};
+
+const SettingsStorageQuotaEnforcer::Limits SettingsFrontend::kLocalQuota = {
+  // Same as localStorage (5MB).
+  5 * 1000 * 1024,
+
+  // No need to be restrictive per key here.
+  UINT_MAX,
+
+  // Ditto.
+  UINT_MAX
+};
+
 // Ref-counted container for a SettingsBackend object.
 class SettingsFrontend::BackendWrapper
     : public base::RefCountedThreadSafe<BackendWrapper> {