DevTools: do not clear console when preserving log

third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js

Index: third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js
diff --git a/third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js b/third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js
index a0d3ec7330acc50102aaad44b17c77a6e25cf9f0..bba7aeec7002b1ee8bde778fbdbd06ad1f0d42b6 100644
--- a/third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js
+++ b/third_party/WebKit/Source/devtools/front_end/console/ConsoleViewMessage.js
@@ -204,7 +204,11 @@ Console.ConsoleViewMessage = class {
           break;
         case ConsoleModel.ConsoleMessage.MessageType.Clear:
           messageElement = createElementWithClass('span', 'console-info');
-          messageElement.textContent = Common.UIString('Console was cleared');
+          messageElement.textContent = ConsoleModel.ConsoleModel.canMessageClearConsole(this._message) ?
+              Common.UIString('Console was cleared') :
+              Common.UIString('console.clear() was prevented from non-main frame or \'Preserve log\'');

[pfeldman, 2017/07/12 21:17:28]

This does not sounds like a consistent sentence to me.

`console.clear() was prevented due to 'Preserve log'` or
`console.clear() from iframe was ignored`

[luoe, 2017/07/13 00:42:03]

Done.

+          messageElement.title =
+              Common.UIString('Clear all messages with ' + UI.shortcutRegistry.shortcutTitleForAction('console.clear'));
           break;
         case ConsoleModel.ConsoleMessage.MessageType.Assert:
           var args = [Common.UIString('Assertion failed:')];