fix jstemplate_builder::UseVersion2

realized the old implementation was over-complicated and could fail if two objects had interleaved, rather than nested, scope.

BUG=none
TEST=manual


Review URL: http://codereview.chromium.org/10269008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@134663 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/jstemplate_builder.cc

@@ -16,19 +16,19 @@
 
 namespace {
 
-// True when building version 2 templates. See UseVersion2 class.
-bool g_version2 = false;
+// Non-zero when building version 2 templates. See UseVersion2 class.
+int g_version2 = 0;
 
 }  // namespace
 
 namespace jstemplate_builder {
 
-UseVersion2::UseVersion2() : previous_value_(g_version2) {
-  g_version2 = true;
+UseVersion2::UseVersion2() {
+  g_version2++;
 }
 
 UseVersion2::~UseVersion2() {
-  g_version2 = previous_value_;
+  g_version2--;
 }
 
 std::string GetTemplateHtml(const base::StringPiece& html_template,

chrome/common/jstemplate_builder.h

@@ -33,8 +33,6 @@ class UseVersion2 {
   ~UseVersion2();
 
  private:
-  bool previous_value_;
-
   DISALLOW_COPY_AND_ASSIGN(UseVersion2);
 };