InterfacePtr: not configure proxy until actual read/write is needed.

InterfacePtr: not setup proxy until actual read/write is needed.

A common usage of InterfacePtr is:
(1) Create a new InterfacePtr instance.
(2) BindToProxy() is called to bind the interface pointer to an implementation.
(3) Immediately, the message pipe handle underneath the interface pointer is detached and sent over another message pipe.

In step (2), currently we do all the setup work for the interface pointer: construct Router and Connector instance, post task to start watching the message pipe handle, etc. All the work is thrown away at step (3).

With this CL, the proxy setup work won't be done until actual read/write is needed.

BUG=394883
TEST=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=284034

[yzshen1, 2014-07-17 23:06:20]

Hi, Darin.

Would you please take a look? Thanks!

[darin (slow to review), 2014-07-18 03:44:45]

LGTM

I'm on the fence about the renaming of router() to router_for_testing(). It is
hidden behind the internal_state() accessor, which is already a good hint that
you shouldn't be using it in production code. However, since we have only needed
the Router accessor in test code thus far, I'm OK with the renaming.

[yzshen1, 2014-07-18 06:34:47]

Thanks Darin!

[yzshen1, 2014-07-18 06:34:57]

The CQ bit was checked by yzshen@chromium.org

[commit-bot: I haz the power, 2014-07-18 06:36:00]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/yzshen@chromium.org/400043004/20001

[commit-bot: I haz the power, 2014-07-18 08:30:12]

Change committed as 284034