Add pause action for key and pointer source types

In Webdriver spec, it has an example:
https://www.w3.org/TR/webdriver/#example-11
that the source has a pause action, which means that the
source does not have any action at this tick. Currently we only have
a pause action for none source type, we should have the pause action
for the key and pointer types as well as per web driver spec:
https://www.w3.org/TR/webdriver/#dfn-pause

For example:
let actions = new test_driver.Actions()
      .addPointer("touchPointer1", "touch")
      .addPointer("touchPointer2", "touch")
      .pointerMove(10, 0, {origin: test1, sourceName: "touchPointer2"})
      .pointerMove(0, 0, {origin: test1, sourceName: "touchPointer1"})
      .pointerDown({sourceName: "touchPointer1"})
      .pointerDown({sourceName: "touchPointer2"})
      .pause(0, "pointer", {sourceName: "touchPointer1"})
      .pointerMove(0, 10, {origin: test1, sourceName: "touchPointer2"})
      .pointerUp({sourceName: "touchPointer1"})
      .pointerUp({sourceName: "touchPointer2"});


Bug: 1020674
Change-Id: Iacd2811a91bc26d273cd9589a96e0a377941d79c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900650Reviewed-by: Navid Zolghadr <nzolghadr@chromium.org>
Reviewed-by: Lan Wei <lanwei@chromium.org>
Commit-Queue: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714370}

third_party/blink/web_tests/external/wpt/resources/testdriver-actions.js

@@ -195,10 +195,16 @@
      * Add a pause to the current tick
      *
      * @param {Number?} duration - Minimum length of the tick in ms.
+     * @param {String} sourceType - source type
+     * @param {String?} sourceName - Named key or pointer source to use or null for the default
+     *                               key or pointer source
      * @returns {Actions}
      */
-    pause: function(duration) {
-      this.getSource("none").addPause(this, duration);
+    pause: function(duration=0, sourceType="none", {sourceName=null}={}) {
+      if (sourceType=="none")
+        this.getSource("none").addPause(this, duration);
+      else
+        this.getSource(sourceType, sourceName).addPause(this, duration);
       return this;
     },
 
@@ -339,6 +345,14 @@
       }
       this.actions.set(tick, {type: "keyUp", value: key});
     },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
   };
 
   function PointerSource(parameters={pointerType: "mouse"}) {
@@ -393,6 +407,14 @@
         this.actions.get(tick).duration = duration;
       }
     },
+
+    addPause: function(actions, duration) {
+      let tick = actions.tickIdx;
+      if (this.actions.has(tick)) {
+        tick = actions.addTick().tickIdx;
+      }
+      this.actions.set(tick, {type: "pause", duration: duration});
+    },
   };
 
   test_driver.Actions = Actions;