Add a convenience function to Version

Came up as in item in a component updater review. It is a common pattern used in extension updater and component updater.

TEST=included
BUG=none
Review URL: http://codereview.chromium.org/7541015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@94928 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 15 insertions, 0 deletions

diff --git a/base/version.cc b/base/version.cc
index cdd15a0..1f9bd20 100644
--- a/base/version.cc
+++ b/base/version.cc
@@ -45,6 +45,13 @@ bool Version::IsValid() const {
   return (!components_.empty());
 }
 
+bool Version::IsOlderThan(const std::string& version_str) const {
+  Version proposed_ver(version_str);
+  if (!proposed_ver.IsValid())
+    return false;
+  return (CompareTo(proposed_ver) < 0);
+}
+
 // TODO(cpu): remove this method.
 Version* Version::GetVersionFromString(const std::string& version_str) {
   Version* vers = new Version(version_str);
diff --git a/base/version.h b/base/version.h
index e03b01a..b61cbb5 100644
--- a/base/version.h
+++ b/base/version.h
@@ -31,6 +31,12 @@ class BASE_API Version {
   // Returns true if the object contains a valid version number.
   bool IsValid() const;
 
+  // Commonly used pattern. Given a valid version object, compare if a
+  // |version_str| results in a newer version. Returns true if the
+  // string represents valid version and if the version is greater than
+  // than the version of this object.
+  bool IsOlderThan(const std::string& version_str) const;
+
   // Returns NULL if the string is not in the proper format.
   // Caller is responsible for freeing the Version object once done.
   // DO NOT USE FOR NEWER CODE.
diff --git a/base/version_unittest.cc b/base/version_unittest.cc
index a3b1ac6..342d0d6 100644
--- a/base/version_unittest.cc
+++ b/base/version_unittest.cc
@@ -85,5 +85,7 @@ TEST_F(VersionTest, Compare) {
     scoped_ptr<Version> rhs(Version::GetVersionFromString(cases[i].rhs));
     EXPECT_EQ(lhs->CompareTo(*rhs), cases[i].expected) <<
           cases[i].lhs << " ? " << cases[i].rhs;
+
+    EXPECT_EQ(lhs->IsOlderThan(cases[i].rhs), (cases[i].expected == -1));
   }
 }