Add MonotonicallyIncreasingTime to V8 Platform.

include/v8-platform.h

Index: include/v8-platform.h
diff --git a/include/v8-platform.h b/include/v8-platform.h
index 1f1679f0e0b60ec7e36281e480cb20d8c8cad64b..7bac11aef069957fc7e22b0a437becdac44b8148 100644
--- a/include/v8-platform.h
+++ b/include/v8-platform.h
@@ -55,6 +55,20 @@ class Platform {
    * scheduling. The definition of "foreground" is opaque to V8.
    */
   virtual void CallOnForegroundThread(Isolate* isolate, Task* task) = 0;
+
+
+  /**
+   * Monotonically increasing time in seconds from an arbitrary fixed point in
+   * the past. This function is expected to return at least
+   * millisecond-precision values. For this reason,
+   * it is recommended that the fixed point be no further in the past than
+   * the epoch.
+   **/
+  virtual double MonotonicallyIncreasingTime() {
+    // TODO(rmcilroy): Remove this default implementation when Chromium
+    // change has landed.
+    return 0;
+  }
 };
 
 }  // namespace v8