Reland 1: "mac: Allow Chrome to hand off its active URL to other devices."

The original CL used instance variables in a class extension and automatic
generation of ivars for synthesized properties, features only available on
64-bit builds. The Mac Memory bots are still compiling Chromium in 32-bits.
This reland removes the usage of those features.

> This CL adds the class HandoffManager, which is responsible for interfacing
> with Apple's Handoff APIs. It takes a GURL, and exposes that GURL to Handoff.
>
> This CL adds the class ActiveWebContentsObserver, which is responsible for
> listening to changes to the active browser, the active tab, and the visible
> URL. It notifies its delegate when any of this state might have changed.
>
> AppControllerMac is the delegate of ActiveWebContentsObserver, as well as the
> owner of the HandoffManager. When it receives a delegate callback, it passes an
> updated GURL to the HandoffManager. There is some minimal logic in
> AppControllerMac that prevents URLs from incognito windows from being passed to
> the HandoffManager.
>
> BUG=431051, 438823
> Committed: https://crrev.com/708abc5b0abb5e0916d779bf6d1342fd472a2aa1
> Cr-Commit-Position: refs/heads/master@{#307846}

BUG=431051, 438823
TBR=sky, erikwright, mmenke, avi

Review URL: https://codereview.chromium.org/794853004

Cr-Commit-Position: refs/heads/master@{#308005}

1 files changed, 47 insertions, 0 deletions

diff --git a/chrome/browser/ui/cocoa/handoff_active_url_observer_bridge.h b/chrome/browser/ui/cocoa/handoff_active_url_observer_bridge.h
new file mode 100644
index 0000000..0d00961
--- /dev/null
+++ b/chrome/browser/ui/cocoa/handoff_active_url_observer_bridge.h
@@ -0,0 +1,47 @@
+// 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.
+
+#ifndef CHROME_BROWSER_UI_COCOA_HANDOFF_ACTIVE_URL_OBSERVER_BRIDGE_H_
+#define CHROME_BROWSER_UI_COCOA_HANDOFF_ACTIVE_URL_OBSERVER_BRIDGE_H_
+
+#import <Cocoa/Cocoa.h>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/ui/cocoa/handoff_active_url_observer_delegate.h"
+
+namespace content {
+class WebContents;
+}
+
+class HandoffActiveURLObserver;
+
+// A protocol that allows ObjC objects to receive delegate callbacks from
+// HandoffActiveURLObserver.
+@protocol HandoffActiveURLObserverBridgeDelegate
+- (void)handoffActiveURLChanged:(content::WebContents*)webContents;
+@end
+
+// This class allows an ObjC object to receive the delegate callbacks from an
+// HandoffActiveURLObserver.
+class HandoffActiveURLObserverBridge : public HandoffActiveURLObserverDelegate {
+ public:
+  explicit HandoffActiveURLObserverBridge(
+      NSObject<HandoffActiveURLObserverBridgeDelegate>* delegate);
+
+  ~HandoffActiveURLObserverBridge() override;
+
+ private:
+  void HandoffActiveURLChanged(content::WebContents* web_contents) override;
+
+  // Instances of this class should be owned by their |delegate_|.
+  NSObject<HandoffActiveURLObserverBridgeDelegate>* delegate_;
+
+  // The C++ object that this class acts as a bridge for.
+  scoped_ptr<HandoffActiveURLObserver> observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(HandoffActiveURLObserverBridge);
+};
+
+#endif  // CHROME_BROWSER_UI_COCOA_HANDOFF_ACTIVE_URL_OBSERVER_BRIDGE_H_