AppShell: Remove some logspam

ShellExtensionsClient::IsScriptableURL() can be called a lot, so it would be
better if it didn't log NOTIMPLEMENTED().

We can consider it to be "implemented".

Bug: None
Change-Id: I4dd42c526d2aa75f3d7146527f1d6dfa7beb20fa
Reviewed-on: https://chromium-review.googlesource.com/967602Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545587}

extensions/shell/common/shell_extensions_client.cc

@@ -154,7 +154,7 @@ URLPatternSet ShellExtensionsClient::GetPermittedChromeSchemeHosts(
 
 bool ShellExtensionsClient::IsScriptableURL(const GURL& url,
                                             std::string* error) const {
-  NOTIMPLEMENTED();
+  // No restrictions on URLs.
   return true;
 }