DevTools: Changes Drawer

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 cf37c6908f6b4a280c0fc50018b39e95c141d596..303a7a0301676d79b9a1608297cd67971c59233a 100644
--- a/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
+++ b/third_party/WebKit/Source/devtools/front_end/workspace/UISourceCode.js
@@ -75,6 +75,7 @@ Workspace.UISourceCode = class extends Common.Object {
     this._workingCopy = null;
     /** @type {?function() : string} */
     this._workingCopyGetter = null;
+    this._mightHaveChanges = false;
   }
 
   /**
@@ -318,6 +319,7 @@ Workspace.UISourceCode = class extends Common.Object {
     if (!lastRevision || lastRevision._content !== this._content) {
       var revision = new Workspace.Revision(this, this._content, new Date());
       this._history.push(revision);
+      this.mightHaveChanges = true;
     }
 
     this._innerResetWorkingCopy();
@@ -331,6 +333,15 @@ Workspace.UISourceCode = class extends Common.Object {
     }
   }
 
+  /**
+   * @return {!Promise<boolean>}
+   */
+  hasChanges() {
+    if (!this.mightHaveChanges)
+      return Promise.resolve(false);
+    return this.requestOriginalContent().then(content => this.mightHaveChanges = content !== this.workingCopy());
+  }
+
   saveAs() {
     Workspace.fileManager.save(this._url, this.workingCopy(), true, callback.bind(this));
     Workspace.fileManager.close(this._url);
@@ -442,6 +453,7 @@ Workspace.UISourceCode = class extends Common.Object {
   }
 
   _workingCopyChanged() {
+    this.mightHaveChanges = true;
     this._removeAllMessages();
     this.dispatchEventToListeners(Workspace.UISourceCode.Events.WorkingCopyChanged, this);
     this._project.workspace().dispatchEventToListeners(