Devtools Animations: Support multiple frames in the animation timeline

Source/devtools/front_end/sdk/AnimationModel.js

Index: Source/devtools/front_end/sdk/AnimationModel.js
diff --git a/Source/devtools/front_end/sdk/AnimationModel.js b/Source/devtools/front_end/sdk/AnimationModel.js
index 573293b402253abe935d0204af9832f2782d23e9..f5e536eb416da1184c37287de997bfc2f5b33203 100644
--- a/Source/devtools/front_end/sdk/AnimationModel.js
+++ b/Source/devtools/front_end/sdk/AnimationModel.js
@@ -13,6 +13,8 @@ WebInspector.AnimationModel = function(target)
     WebInspector.SDKModel.call(this, WebInspector.AnimationModel, target);
     this._agent = target.animationAgent();
     target.registerAnimationDispatcher(new WebInspector.AnimationDispatcher(this));
+    /** @type {!Map.<string, !WebInspector.AnimationModel.AnimationPlayer>} */
+    this._animationsMap = new Map();
 }
 
 WebInspector.AnimationModel.Events = {
@@ -52,6 +54,9 @@ WebInspector.AnimationModel.prototype = {
     animationPlayerCreated: function(payload, resetTimeline)
     {
         var player = WebInspector.AnimationModel.AnimationPlayer.parsePayload(this.target(), payload);
+        if (resetTimeline)
+            this._animationsMap.clear();
+        this._animationsMap.set(player.id(), player);
         this.dispatchEventToListeners(WebInspector.AnimationModel.Events.AnimationPlayerCreated, { "player": player, "resetTimeline": resetTimeline });
     },
 
@@ -63,6 +68,51 @@ WebInspector.AnimationModel.prototype = {
         this.dispatchEventToListeners(WebInspector.AnimationModel.Events.AnimationPlayerCanceled, { "playerId": playerId });
     },
 
+    /**
+     * @param {function(?Array.<!AnimationAgent.AnimationStartTime>)} userCallback
+     * @param {?Protocol.Error} error
+     * @param {!Array.<!AnimationAgent.AnimationStartTime>} startTimes
+     */
+    _updateStartTimes: function(userCallback, error, startTimes)
+    {
+        if (error) {
+            userCallback(null);
+            return;
+        }
+        for (var player of startTimes) {
+            var animation = this._animationsMap.get(player.id);
+            console.assert(animation);
+            animation._updateStartTime(player.startTime);
+        }
+        userCallback(startTimes);
+    },
+
+    /**
+     * @param {number} playbackRate
+     * @param {function(?Array.<!AnimationAgent.AnimationStartTime>)} userCallback
+     */
+    setPlaybackRate: function(playbackRate, userCallback)
+    {
+        this._agent.setPlaybackRate(playbackRate, this._updateStartTimes.bind(this, userCallback));
+    },
+
+    /**
+     * @param {number} time
+     * @param {function(?Array.<!AnimationAgent.AnimationStartTime>)} userCallback
+     */
+    seekTimelineTo: function(time, userCallback)
+    {
+        this._agent.seekTimelineTo(time, this._updateStartTimes.bind(this, userCallback));
+    },
+
+    /**
+     * @param {number} timeDelta
+     */
+    seekTimelineBy: function(timeDelta)
+    {
+        this._agent.seekTimelineBy(timeDelta);
+    },
+
     ensureEnabled: function()
     {
         if (this._enabled)
@@ -159,7 +209,15 @@ WebInspector.AnimationModel.AnimationPlayer.prototype = {
      */
     startTime: function()
     {
-        return this._payload.startTime;
+        return this._startTime === undefined ? this._payload.startTime : this._startTime;
+    },
+
+    /**
+     * @param {number} startTime
+     */
+    _updateStartTime: function(startTime)
+    {
+        this._startTime = startTime;
     },
 
     /**