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

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

Committed: https://crrev.com/600f7962455cb8479168eb2c6678eda05365460a
Cr-Commit-Position: refs/heads/master@{#308005}

[erikchen, 2014-12-11 19:49:33]

Patchset #2 (id:20001) has been deleted

[erikchen, 2014-12-11 21:18:42]

Patchset #2 (id:40001) has been deleted

[erikchen, 2014-12-11 21:24:22]

erikchen@chromium.org changed reviewers:
+ avi@chromium.org

[erikchen, 2014-12-11 21:24:48]

erikchen@chromium.org changed reviewers:
+ avi@chromium.org

[Avi (use Gerrit), 2014-12-11 21:37:02]

avi@chromium.org changed reviewers:
+ avi@chromium.org

[erikchen, 2014-12-11 21:40:43]

On 2014/12/11 21:37:02, Avi wrote:
> mailto:avi@chromium.org changed reviewers:
> + mailto:avi@chromium.org

AppEngine is having problems. Quoting an email exchange:

Me:
"""
I changed the CL to not rely on language features only present in 64-bit builds.
You only need to review the diff between patch sets 1 and 2, although you are
welcome to re-review the whole thing.

Given that the changes only affected the Mac-code, I'm tbr'ing the other
reviewers.
"""

avi:
"""
LGTM, but try to use @private in HandoffManager.
"""

[erikchen, 2014-12-11 21:44:17]

On 2014/12/11 21:40:43, erikchen wrote:
> On 2014/12/11 21:37:02, Avi wrote:
> > mailto:avi@chromium.org changed reviewers:
> > + mailto:avi@chromium.org
> 
> AppEngine is having problems. Quoting an email exchange:
> 
> Me:
> """
> I changed the CL to not rely on language features only present in 64-bit
builds.
> You only need to review the diff between patch sets 1 and 2, although you are
> welcome to re-review the whole thing.
> 
> Given that the changes only affected the Mac-code, I'm tbr'ing the other
> reviewers.
> """
> 
> avi:
> """
> LGTM, but try to use @private in HandoffManager.
> """

Responded to comment from avi in patch set 3. Moving avi to tbr@, even though
he's lgtm'ed this CL, since this Rietveld is having problems.

[erikchen, 2014-12-11 21:45:08]

The CQ bit was checked by erikchen@chromium.org

[commit-bot: I haz the power, 2014-12-11 23:08:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/794853004/80001

[commit-bot: I haz the power, 2014-12-12 00:17:45]

Committed patchset #3 (id:80001)

[commit-bot: I haz the power, 2014-12-12 00:19:18]

Patchset 3 (id:??) landed as
https://crrev.com/600f7962455cb8479168eb2c6678eda05365460a
Cr-Commit-Position: refs/heads/master@{#308005}