DevTools: introduce object previews experiment

third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js

Index: third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js
diff --git a/third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js b/third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js
index 47d2893dadbb1a1f117593fd1b153a233c012340..24648d9471ee30c4434304dd48a8cf4c11186ee4 100644
--- a/third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js
+++ b/third_party/WebKit/Source/devtools/front_end/components/ObjectPropertiesSection.js
@@ -219,15 +219,17 @@ Components.ObjectPropertiesSection = class extends TreeOutlineInShadow {
    * @param {boolean} wasThrown
    * @param {!Element=} parentElement
    * @param {!Components.Linkifier=} linkifier
+   * @param {boolean=} hidePreview
    * @return {!Element}
    */
-  static createValueElementWithCustomSupport(value, wasThrown, parentElement, linkifier) {
+  static createValueElementWithCustomSupport(value, wasThrown, parentElement, linkifier, hidePreview) {
     if (value.customPreview()) {
       var result = (new Components.CustomPreviewComponent(value)).element;
       result.classList.add('object-properties-section-custom-section');
       return result;
     }
-    return Components.ObjectPropertiesSection.createValueElement(value, wasThrown, parentElement, linkifier);
+    return Components.ObjectPropertiesSection.createValueElement(
+        value, wasThrown, parentElement, linkifier, hidePreview);
   }
 
   /**
@@ -235,9 +237,10 @@ Components.ObjectPropertiesSection = class extends TreeOutlineInShadow {
    * @param {boolean} wasThrown
    * @param {!Element=} parentElement
    * @param {!Components.Linkifier=} linkifier
+   * @param {boolean=} hidePreview
    * @return {!Element}
    */
-  static createValueElement(value, wasThrown, parentElement, linkifier) {
+  static createValueElement(value, wasThrown, parentElement, linkifier, hidePreview) {
     var valueElement;
     var type = value.type;
     var subtype = value.subtype;
@@ -264,8 +267,13 @@ Components.ObjectPropertiesSection = class extends TreeOutlineInShadow {
         parentElement.classList.add('hbox');
     } else {
       valueElement = createElementWithClass('span', 'object-value-' + (subtype || type));
-      valueElement.setTextContentTruncatedIfNeeded(description);
       valueElement.title = description;
+      if (value.preview && !hidePreview) {
+        var previewFormatter = new Components.RemoteObjectPreviewFormatter();
+        previewFormatter.appendObjectPreview(valueElement, value.preview);
+      } else {
+        valueElement.setTextContentTruncatedIfNeeded(description);
+      }
     }
 
     if (wasThrown) {
@@ -781,8 +789,9 @@ Components.ObjectPropertyTreeElement = class extends TreeElement {
     separatorElement.textContent = ': ';
 
     if (this.property.value) {
+      var hidePreview = this.property.name === '__proto__' || !Runtime.experiments.isEnabled('objectPreviews');
       this.valueElement = Components.ObjectPropertiesSection.createValueElementWithCustomSupport(
-          this.property.value, this.property.wasThrown, this.listItemElement, this._linkifier);
+          this.property.value, this.property.wasThrown, this.listItemElement, this._linkifier, hidePreview);
       this.valueElement.addEventListener('contextmenu', this._contextMenuFired.bind(this, this.property), false);
     } else if (this.property.getter) {
       this.valueElement = Components.ObjectPropertyTreeElement.createRemoteObjectAccessorPropertySpan(