DevTools: update search-across-all-files placeholder tip

The current tip wording is the following: "Use 'file:' to define search scope".
The patch changes wording to: "Enter query, use `file:` to filter by path".

BUG=488112
NOTRY=true
TBR=pfeldman, paulirish

Review URL: https://codereview.chromium.org/1317223002

git-svn-id: svn://svn.chromium.org/blink/trunk@201357 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/devtools/front_end/sources/AdvancedSearchView.js

@@ -24,7 +24,7 @@ WebInspector.AdvancedSearchView = function()
 
     this._search = WebInspector.HistoryInput.create();
     this._searchPanelElement.appendChild(this._search);
-    this._search.placeholder = WebInspector.UIString("Use 'file:' to define search scope");
+    this._search.placeholder = WebInspector.UIString("Enter query, use `file:` to filter by path");
     this._search.setAttribute("type", "text");
     this._search.classList.add("search-config-search");
     this._search.setAttribute("results", "0");