Upstream web_controller_provider and dependencies

ios/web/web_state/ui/web_view_js_utils.mm

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/web/web_state/ui/web_view_js_utils.h"
+
+#import <UIKit/UIKit.h>
+#import <WebKit/WebKit.h>
+
+#include "base/ios/weak_nsobject.h"
+#include "base/logging.h"
+#include "base/mac/scoped_nsobject.h"
+
+namespace {
+
+// Converts result of WKWebView script evaluation to UIWebView format.
+NSString* UIResultFromWKResult(id result) {
+  if (!result)
+    return @"";
+
+  CFTypeID result_type = CFGetTypeID(result);
+  if (result_type == CFStringGetTypeID())
+    return result;
+
+  if (result_type == CFNumberGetTypeID())
+    return [result stringValue];
+
+  if (result_type == CFBooleanGetTypeID())
+    return [result boolValue] ? @"true" : @"false";
+
+  // TODO(stuartmorgan): Stringify other types.
+  NOTREACHED();
+  return nil;
+}
+
+}  // namespace
+
+namespace web {
+
+void EvaluateJavaScript(UIWebView* web_view,
+                        NSString* script,
+                        JavaScriptCompletion completion_handler) {
+  base::WeakNSObject<UIWebView> weak_web_view(web_view);
+  dispatch_async(dispatch_get_main_queue(), ^{
+      NSString* result =
+          [weak_web_view stringByEvaluatingJavaScriptFromString:script];
+      if (completion_handler)
+        completion_handler(result, nil);
+  });
+}
+
+void EvaluateJavaScript(WKWebView* web_view,
+                        NSString* script,
+                        JavaScriptCompletion completion_handler) {
+  DCHECK([script length]);
+  id web_view_completion_handler = nil;

[droger, 2015/02/19 10:51:04]

Why id?

[sdefresne, 2015/02/19 13:39:08]

Good catch.

+  // Do not create a web_view_completion_handler if no |handler| is passed to
+  // this function. This results in no creation of an unnecessary block.
+  if (completion_handler) {
+    // WKWebView crashes on deallocation when it flushes scripts that did not
+    // finish the execution but have |completion_handler|. Passing
+    // |completion_handler| ownership to the block itself and keeping it alive
+    // until it's executed fixes the crash. No memory leak is expected since
+    // |completion_handler| is always executed even if WKWebView is deallocated.
+    // https://bugs.webkit.org/show_bug.cgi?id=140203
+    web_view_completion_handler = [^(id result, NSError* error) {
+      completion_handler(UIResultFromWKResult(result), error);
+      [web_view_completion_handler autorelease];

[droger, 2015/02/19 10:51:04]

This looks like a bug.
I think that the block captures web_view_completion_handler by value (since the
variable is not __block), and thus it is nil (as defined on line 56 above).

I am not sure what the intent was, but maybe the variable should be declared as
__block.

stuartmorgan: can you comment on this?

[sdefresne, 2015/02/19 13:39:08]

I no longer require this file, so the question applies to the downstream version
of the file.

[stuartmorgan, 2015/02/19 14:23:54]

Yep, this does look worrying. I'll investigate.

[Eugene But (OOO till 7-30), 2015/02/23 03:20:11]

What exactly looks wrong to you? Functionality or memory management? AFAIK
__block keyword is required only if variable is changed inside the block.

+    } copy];
+  }
+  [web_view evaluateJavaScript:script
+             completionHandler:web_view_completion_handler];
+}
+
+}  // namespace web