[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js

Index: third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js
diff --git a/third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js b/third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js
index d02ce0a5f8de7668078bb081ce7cd6fe1b16fb33..9dc6932b2d24f7f10b5bf92d0226cb2f09e2b0c3 100644
--- a/third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js
+++ b/third_party/WebKit/Source/devtools/front_end/bindings/StylesSourceMapping.js
@@ -44,7 +44,7 @@ WebInspector.StylesSourceMapping = function(cssModel, workspace, networkMapping)
     this._workspace.addEventListener(WebInspector.Workspace.Events.UISourceCodeRemoved, this._uiSourceCodeRemoved, this);
     this._networkMapping = networkMapping;
 
-    cssModel.target().resourceTreeModel.addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._unbindAllUISourceCodes, this);
+    cssModel.resourceTreeModel().addEventListener(WebInspector.ResourceTreeModel.EventTypes.MainFrameNavigated, this._unbindAllUISourceCodes, this);

[pfeldman, 2016/07/13 23:55:57]

This isn't nice - we should keep models of different domains independent as much
as we can. You could introduce this navigation event on Target itself to
mitigate it here.

[dgozman, 2016/07/14 16:29:28]

I'm not that sure. DOM only makes sense together with frames, and our dom nodes
operate with frame ids. Should we say that these domains come together as a
group?

[eostroukhov-old, 2016/07/20 23:46:15]

Switched to TargetManager event

 
     this._cssModel.addEventListener(WebInspector.CSSModel.Events.StyleSheetChanged, this._styleSheetChanged, this);
     /** @type {!Map<string, !Map<string, !Map<string, !WebInspector.CSSStyleSheetHeader>>>} */