Move Version to base namespace.

Adds "using base::Version" to the header to avoid having to update everything at
once. All forward declares and the locations where the forward declares are
used are updated.

Review URL: https://chromiumcodereview.appspot.com/14099010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195456 0039d316-1c4b-4281-b951-d872f2087c98

• base/version.cc[diff]
• base/version.h[diff]
• chrome/browser/component_updater/flash_component_installer.h[diff]
• chrome/browser/component_updater/pnacl/pnacl_component_installer.h[diff]
• chrome/browser/extensions/api/runtime/runtime_api.h[diff]
• chrome/browser/extensions/extension_service.h[diff]
• chrome/browser/extensions/external_provider_impl.h[diff]
• chrome/browser/extensions/external_provider_interface.h[diff]
• chrome/browser/extensions/pending_extension_manager.h[diff]
• chrome/browser/extensions/updater/extension_downloader.h[diff]
• chrome/common/extensions/extension.h[diff]
• chrome/installer/setup/install_worker.h[diff]
• chrome/installer/setup/setup_util.h[diff]
• chrome/installer/test/alternate_version_generator.h[diff]
• chrome/installer/util/install_util.h[diff]
• chrome/installer/util/installation_state.h[diff]
• chrome/installer/util/installer_state.h[diff]
• chrome_frame/dll_redirector.h[diff]
• webkit/plugins/npapi/plugin_utils.h[diff]