Fixit: Fork base::TimeTicks --> TimeTicks + ThreadTicks + TraceTicks

TimeTicks was being overused for time values from three different clock
sources.  This change splits the class into three separate classes: The
general-purpose monotonic time (TimeTicks), the thread-local run time
(ThreadTicks), and the global system trace time (TraceTicks).  With this
change, the compiler is now able to use type-checking to guarantee
values from different clocks are not being mixed when doing time math.

This is the 2nd in a two-part change.  Part 1 factored-out the
comparison and math operator overloads common to base::Time and
base::TimeTicks into a templated base class.  The new ThreadTicks and
TraceTicks time classes also inherit from that base class.

Updated base/trace_event/* and a handful of outside-of-base uses of
ThreadNow() and NowFromSystemTraceTime() to use the new classes.  A bug
was identified and fixed, in src/ui/gl/angle_platform_impl.cc, where
values from TimeTicks::Now() were being erroneously provided to
base::TraceEvent instead of values from NowFromSystemTraceTime().

BUG=467417
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
NOTRY=true

Review URL: https://codereview.chromium.org/1122153002

Cr-Commit-Position: refs/heads/master@{#332080}

2 files changed, 28 insertions, 0 deletions

diff --git a/ipc/ipc_message_utils.cc b/ipc/ipc_message_utils.cc
index a00e857..58dc510 100644
--- a/ipc/ipc_message_utils.cc
+++ b/ipc/ipc_message_utils.cc
@@ -660,6 +660,25 @@ void ParamTraits<base::TimeTicks>::Log(const param_type& p, std::string* l) {
   ParamTraits<int64>::Log(p.ToInternalValue(), l);
 }
 
+void ParamTraits<base::TraceTicks>::Write(Message* m, const param_type& p) {
+  ParamTraits<int64>::Write(m, p.ToInternalValue());
+}
+
+bool ParamTraits<base::TraceTicks>::Read(const Message* m,
+                                         PickleIterator* iter,
+                                         param_type* r) {
+  int64 value;
+  bool ret = ParamTraits<int64>::Read(m, iter, &value);
+  if (ret)
+    *r = base::TraceTicks::FromInternalValue(value);
+
+  return ret;
+}
+
+void ParamTraits<base::TraceTicks>::Log(const param_type& p, std::string* l) {
+  ParamTraits<int64>::Log(p.ToInternalValue(), l);
+}
+
 void ParamTraits<IPC::ChannelHandle>::Write(Message* m, const param_type& p) {
 #if defined(OS_WIN)
   // On Windows marshalling pipe handle is not supported.
diff --git a/ipc/ipc_message_utils.h b/ipc/ipc_message_utils.h
index 71bfbdf..1e3ee0c 100644
--- a/ipc/ipc_message_utils.h
+++ b/ipc/ipc_message_utils.h
@@ -55,6 +55,7 @@ class NullableString16;
 class Time;
 class TimeDelta;
 class TimeTicks;
+class TraceTicks;
 struct FileDescriptor;
 }
 
@@ -503,6 +504,14 @@ struct IPC_EXPORT ParamTraits<base::TimeTicks> {
 };
 
 template <>
+struct IPC_EXPORT ParamTraits<base::TraceTicks> {
+  typedef base::TraceTicks param_type;
+  static void Write(Message* m, const param_type& p);
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+template <>
 struct ParamTraits<base::Tuple<>> {
   typedef base::Tuple<> param_type;
   static void Write(Message* m, const param_type& p) {