Ensure media's buffered ranges always have a range that includes currentTime.

media/base/ranges.h

Index: media/base/ranges.h
diff --git a/media/base/ranges.h b/media/base/ranges.h
index 1117ae58b8db86321df815f07f1646d996f3a299..82bf7a074742681cebafa997543fbaf4b16bc085 100644
--- a/media/base/ranges.h
+++ b/media/base/ranges.h
@@ -11,6 +11,7 @@
 
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/time.h"
 #include "media/base/media_export.h"
 
 namespace media {
@@ -41,6 +42,9 @@ class Ranges {
   Ranges<T> IntersectionWith(const Ranges<T>& other);
 
  private:
+  // Wrapper around DCHECK_LT allowing comparisons of operator<<'able T's.
+  void DCheckLT(const T& lhs, const T& rhs) const;
+
   // Disjoint, in increasing order of start.
   std::vector<std::pair<T, T> > ranges_;
 };
@@ -54,7 +58,7 @@ size_t Ranges<T>::Add(T start, T end) {
   if (start == end)  // Nothing to be done with empty ranges.
     return ranges_.size();
 
-  DCHECK(start < end);
+  DCheckLT(start, end);
   size_t i;
   // Walk along the array of ranges until |start| is no longer larger than the
   // current interval's end.
@@ -99,6 +103,15 @@ size_t Ranges<T>::Add(T start, T end) {
   return ranges_.size();
 }
 
+template<>
+void Ranges<base::TimeDelta>::DCheckLT(const base::TimeDelta& lhs,
+                                       const base::TimeDelta& rhs) const;
+
+template<class T>
+void Ranges<T>::DCheckLT(const T& lhs, const T& rhs) const {
+  DCHECK_LT(lhs, rhs);
+}
+
 template<class T>
 size_t Ranges<T>::size() const {
   return ranges_.size();