DevTools: Cache the original content on UISourceCode

third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js

Index: third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
diff --git a/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js b/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
index 7872902a8c3287ff3140427ab810e47d36659a70..5b5af0f122ddae48b0fbfc11aa421b962cc153fb 100644
--- a/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
+++ b/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
@@ -68,6 +68,8 @@ Workspace.UISourceCode = class extends Common.Object {
     this._messages = [];
 
     this._contentLoaded = false;
+    /** @type {?Promise<?string>} */
+    this._originalContentPromise = null;
     /** @type {?string} */
     this._content = null;
     this._forceLoadOnCheckContent = false;
@@ -289,10 +291,12 @@ Workspace.UISourceCode = class extends Common.Object {
    * @return {!Promise<?string>}
    */
   requestOriginalContent() {
-    var callback;
-    var promise = new Promise(fulfill => callback = fulfill);
-    this._project.requestFileContent(this, callback);
-    return promise;
+    if (this._originalContentPromise)
+      return this._originalContentPromise;
+    var fulfill;
+    this._originalContentPromise = new Promise(x => fulfill = x);
+    this._project.requestFileContent(this, fulfill);
+    return this._originalContentPromise;
   }
 
   /**
@@ -300,7 +304,8 @@ Workspace.UISourceCode = class extends Common.Object {
    */
   _commitContent(content) {
     if (this._project.canSetFileContent()) {
-      this._project.setFileContent(this, content, function() {});
+      // Cache the original content before we overwrite it.
+      this.requestOriginalContent().then(() => this._project.setFileContent(this, content, function() {}));

[lushnikov, 2016/12/20 01:05:23]

this should be in filesystemworkspacebindings

     } else if (this._url && Workspace.fileManager.isURLSaved(this._url)) {
       Workspace.fileManager.save(this._url, content, false, function() {});
       Workspace.fileManager.close(this._url);