[DevTools] Issue zoom from DevToolsWindow instead of browser commands.

[DevTools] Issue zoom from DevToolsWindow instead of browser commands.

This helps to avoid confusion when wrench menu zoom affects DevTools instead
of the page.

BUG=343816
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251448

[dgozman, 2014-02-14 13:21:14]

Could you please take a look?

Unfortunately, previous approach was confusing, since UI elements are expected
to zoom the inspected page, not DevTools.

@tsepez, please review devtools_embedder_message_dispatcher.

[vsevik, 2014-02-14 13:34:39]

lgtm

[jochen (gone - plz use gerrit), 2014-02-14 14:19:16]

lgtm

[jochen (gone - plz use gerrit), 2014-02-14 14:19:17]

lgtm

lgtm

[dgozman, 2014-02-14 14:45:39]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2014-02-14 14:45:53]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dgozman@chromium.org/165213006/1

[commit-bot: I haz the power, 2014-02-14 15:12:46]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-02-14 15:12:47]

Retried try job too often on chromium_presubmit for step(s) presubmit
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=chromium_p...

[Tom Sepez, 2014-02-14 19:12:05]

lgtm

[dgozman, 2014-02-14 20:17:22]

The CQ bit was checked by dgozman@chromium.org

[commit-bot: I haz the power, 2014-02-14 20:20:15]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dgozman@chromium.org/165213006/1

[commit-bot: I haz the power, 2014-02-15 00:15:01]

Change committed as 251448