Convert Devtools protocol Input timestamp to monotonic clock

content/browser/devtools/protocol/input_handler.cc

Index: content/browser/devtools/protocol/input_handler.cc
diff --git a/content/browser/devtools/protocol/input_handler.cc b/content/browser/devtools/protocol/input_handler.cc
index d9c17f3ee0e31fcdfe16e7f6c0785b4df16b9433..3dd2f5b73d8df2ac1fff5469485484cf4ab5cbcd 100644
--- a/content/browser/devtools/protocol/input_handler.cc
+++ b/content/browser/devtools/protocol/input_handler.cc
@@ -69,8 +69,13 @@ void SetEventModifiers(blink::WebInputEvent* event, const int* modifiers) {
 }
 
 void SetEventTimestamp(blink::WebInputEvent* event, const double* timestamp) {
-  event->timeStampSeconds =
-      timestamp ? *timestamp : base::Time::Now().ToDoubleT();
+  // Convert timestamp, in seconds since unix epoch, to an event timestamp
+  // which is time ticks since platform start time.
+  base::TimeTicks ticks = timestamp
+                              ? base::TimeDelta::FromSecondsD(*timestamp) +
+                                    base::TimeTicks::UnixEpoch()
+                              : base::TimeTicks::Now();
+  event->timeStampSeconds = (ticks - base::TimeTicks()).InSecondsF();
 }
 
 bool SetKeyboardEventText(blink::WebUChar* to, const std::string* from) {