[Devtools] Lazily build reverse mappings

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @constructor
  * @param {!WebInspector.DebuggerWorkspaceBinding} debuggerWorkspaceBinding
  * @param {!WebInspector.NetworkMapping} networkMapping
  * @implements {WebInspector.TargetManager.Observer}
  */
@@ skipping 133 matching lines @@
      * @return {!Promise<undefined>}
      */
     sourceMapLoaded: function(script, sourceMap)
     {
         if (!sourceMap)
             return Promise.resolve();
         var previousScriptState = this._scriptPositions(script);
         if (!previousScriptState)
             return Promise.resolve();
 
+        var hasBlackboxedMappings = false;

[lushnikov, 2016/09/28 16:48:12]

what's this code about?

[eostroukhov, 2016/09/28 23:26:33]

There is no reason to check individual mappings if no source URLs from the
source map are blackboxed.

I rewrote the code a bit to make the change smaller.

[lushnikov, 2016/09/29 16:29:52]

Nice, thanks

+        for (var scriptURL of sourceMap.sourceURLs()) {
+            if (this.isBlackboxedURL(scriptURL)) {
+                hasBlackboxedMappings = true;
+                break;
+            }
+        }
+        if (!hasBlackboxedMappings) {
+            if (previousScriptState.length > 0)
+                return this._setScriptState(script, []);
+            return Promise.resolve();
+        }
+
         var mappings = sourceMap.mappings().slice();
         mappings.sort(mappingComparator);
 
         if (!mappings.length) {
             if (previousScriptState.length > 0)
                 return this._setScriptState(script, []);
             return Promise.resolve();
         }
 
         var currentBlackboxed = false;
@@ skipping 289 matching lines @@
             if (scheme === "chrome-extension")
                 prefix += parsedURL.host + "\\b";
             prefix += ".*";
         }
         return prefix + name.escapeForRegExp() + (url.endsWith(name) ? "$" : "\\b");
     }
 }
 
 /** @type {!WebInspector.BlackboxManager} */
 WebInspector.blackboxManager;