Tweak SVNVersion be happier (matches windows).

Fix about:version so "Developer build" says "Official build" when
relevant, and lists SVN version for developer builds.

BUG=12064


Review URL: http://codereview.chromium.org/118036

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17337 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/file_version_info_mac.mm b/base/file_version_info_mac.mm
index 00f470b..70900036 100644
--- a/base/file_version_info_mac.mm
+++ b/base/file_version_info_mac.mm
@@ -103,11 +103,15 @@
 }
 
 std::wstring FileVersionInfo::last_change() {
-  return L"";
+  return GetStringValue(L"SVNRevision");
 }
 
 bool FileVersionInfo::is_official_build() {
+#if defined (GOOGLE_CHROME_BUILD)
+  return true;
+#else
   return false;
+#endif
 }
 
 bool FileVersionInfo::GetValue(const wchar_t* name, std::wstring* value_str) {