Move component updater artifacts into component_updater namespace.

chrome/browser/component_updater/default_component_installer.h

Index: chrome/browser/component_updater/default_component_installer.h
diff --git a/chrome/browser/component_updater/default_component_installer.h b/chrome/browser/component_updater/default_component_installer.h
index 4237f6da8e012d7dea91a48317a4e9a4252ef595..1405b3573bd98fd859cbfc11612cf2eaf30c6691 100644
--- a/chrome/browser/component_updater/default_component_installer.h
+++ b/chrome/browser/component_updater/default_component_installer.h
@@ -18,6 +18,8 @@ class DictionaryValue;
 class FilePath;
 }  // namespace base
 
+namespace component_updater {
+
 // Components should use a DefaultComponentInstaller by defining a class that
 // implements the members of ComponentInstallerTraits, and then registering a
 // DefaultComponentInstaller that has been constructed with an instance of that
@@ -103,4 +105,6 @@ class DefaultComponentInstaller : public ComponentInstaller {
   DISALLOW_COPY_AND_ASSIGN(DefaultComponentInstaller);
 };
 
+}  // namespace component_updater
+
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_