Add plumbing for testing API for MockWebDeviceMotionHandler injection.

Adds methods to set a mock WebDeviceMotionProvider in the Platform layer for testing Device Motion API in Blink.

BUG=135804

[jochen (gone - plz use gerrit), 2013-05-21 07:35:09]

For other mocks, we added a ContentRendererClient::OverrideFoo() method. Why not
use the same pattern here?

[timvolodine, 2013-05-21 12:06:39]

On 2013/05/21 07:35:09, jochen wrote:
> For other mocks, we added a ContentRendererClient::OverrideFoo() method. Why
not
> use the same pattern here?

I see, in this case we want to inject a mock listener from TestRunner into the
platform (similar to gamepad), so the client approach does not look the most
appropriate as it would not expose the mock directly to TestRunner..

[jochen (gone - plz use gerrit), 2013-05-21 12:14:43]

I'm not sure I understand.

for gamepads, we don't create a custom mock object, but just inject some test
data.

In your case, you need to replace the entire handler with a mock.

I think the gamepad solution is not a good model for what you're trying to
achieve. I'd recommend the model the geolocation system uses.

[timvolodine, 2013-05-21 12:17:41]

On 2013/05/21 12:14:43, jochen wrote:
> I'm not sure I understand.
> 
> for gamepads, we don't create a custom mock object, but just inject some test
> data.
> 
> In your case, you need to replace the entire handler with a mock.
> 
> I think the gamepad solution is not a good model for what you're trying to
> achieve. I'd recommend the model the geolocation system uses.

geolocation uses a client-model and does not go through the Platform.h so it is
pretty different in that respect.

[jochen (gone - plz use gerrit), 2013-05-21 12:19:15]

sorry, you're right

What about Hyphenation or any of the other mocks we inject into Platform?

[timvolodine, 2013-05-21 12:27:44]

On 2013/05/21 12:19:15, jochen wrote:
> sorry, you're right
> 
> What about Hyphenation or any of the other mocks we inject into Platform?

It looks like all the others (except gamepad) do not require javascript bindings
and are not tested through TestRunner. For example Hyphenation has a mock in
test_webkit_platform_support.h, while TestRunner uses
renderer_webkitplatformsupport_impl..

[jochen (gone - plz use gerrit), 2013-07-25 13:12:02]

this CL is obsolete now, right?

[timvolodine, 2013-07-25 14:04:52]

On 2013/07/25 13:12:02, jochen wrote:
> this CL is obsolete now, right?

correct, I'll close it.