Fix Time::FromDoubleT so that it will return null time when 0 is passed.

This is the rework of this issue before previous submit is reverted. We need to
fix the usage of Time::FromDoubleT(0) in extension history API.

BUG=none
TEST=non

Review URL: http://codereview.chromium.org/3295001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@58953 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 24 insertions, 3 deletions

diff --git a/base/time.cc b/base/time.cc
index 383f939..766f599 100644
--- a/base/time.cc
+++ b/base/time.cc
@@ -66,6 +66,8 @@ time_t Time::ToTimeT() const {
 
 // static
 Time Time::FromDoubleT(double dt) {
+  if (dt == 0)
+    return Time();  // Preserve 0 so we can tell it doesn't exist.
   return Time(static_cast<int64>((dt *
                                   static_cast<double>(kMicrosecondsPerSecond)) +
                                  kTimeTToMicrosecondsOffset));
@@ -78,6 +80,13 @@ double Time::ToDoubleT() const {
           static_cast<double>(kMicrosecondsPerSecond));
 }
 
+// static
+Time Time::UnixEpoch() {
+  Time time;
+  time.us_ = kTimeTToMicrosecondsOffset;
+  return time;
+}
+
 Time Time::LocalMidnight() const {
   Exploded exploded;
   LocalExplode(&exploded);
diff --git a/base/time.h b/base/time.h
index 0f5eb5d..0ed7957 100644
--- a/base/time.h
+++ b/base/time.h
@@ -230,6 +230,9 @@ class Time {
     return us_ == 0;
   }
 
+  // Returns the time for epoch in Unix-like system (Jan 1, 1970).
+  static Time UnixEpoch();
+
   // Returns the current time. Watch out, the system might adjust its clock
   // in which case time will actually go backwards. We don't guarantee that
   // times are increasing, or that two calls to Now() won't be the same.
@@ -249,6 +252,9 @@ class Time {
 
   // Converts time to/from a double which is the number of seconds since epoch
   // (Jan 1, 1970).  Webkit uses this format to represent time.
+  // Because WebKit initializes double time value to 0 to indicate "not
+  // initialized", we map it to empty Time object that also means "not
+  // initialized".
   static Time FromDoubleT(double dt);
   double ToDoubleT() const;
 
diff --git a/chrome/browser/extensions/extension_cookies_api.cc b/chrome/browser/extensions/extension_cookies_api.cc
index 5a2d456..e22213d 100644
--- a/chrome/browser/extensions/extension_cookies_api.cc
+++ b/chrome/browser/extensions/extension_cookies_api.cc
@@ -306,7 +306,10 @@ bool SetCookieFunction::RunImpl() {
       EXTENSION_FUNCTION_VALIDATE(
           expiration_date_value->GetAsReal(&expiration_date));
     }
-    expiration_time_ = base::Time::FromDoubleT(expiration_date);
+    // Time::FromDoubleT converts double time 0 to empty Time object. So we need
+    // to do special handling here.
+    expiration_time_ = (expiration_date == 0) ?
+        base::Time::UnixEpoch() : base::Time::FromDoubleT(expiration_date);
   }
 
   URLRequestContextGetter* store_context = NULL;
diff --git a/chrome/browser/extensions/extension_history_api.cc b/chrome/browser/extensions/extension_history_api.cc
index 515e918b..fac0e1f 100644
--- a/chrome/browser/extensions/extension_history_api.cc
+++ b/chrome/browser/extensions/extension_history_api.cc
@@ -180,7 +180,10 @@ bool HistoryFunction::GetTimeFromValue(Value* value, base::Time* time) {
   // The history service has seconds resolution, while javascript Date() has
   // milliseconds resolution.
   double seconds_from_epoch = ms_from_epoch / 1000.0;
-  *time = base::Time::FromDoubleT(seconds_from_epoch);
+  // Time::FromDoubleT converts double time 0 to empty Time object. So we need
+  // to do special handling here.
+  *time = (seconds_from_epoch == 0) ?
+      base::Time::UnixEpoch() : base::Time::FromDoubleT(seconds_from_epoch);
   return true;
 }
 
@@ -368,7 +371,7 @@ bool DeleteAllHistoryFunction::RunAsyncImpl() {
   HistoryService* hs = profile()->GetHistoryService(Profile::EXPLICIT_ACCESS);
   hs->ExpireHistoryBetween(
       restrict_urls,
-      base::Time::FromDoubleT(0),  // From the beginning of the epoch.
+      base::Time::UnixEpoch(),     // From the beginning of the epoch.
       base::Time::Now(),           // To the current time.
       &cancelable_consumer_,
       NewCallback(this, &DeleteAllHistoryFunction::DeleteComplete));