Add the Copresence API.

chrome/common/extensions/permissions/chrome_api_permissions.cc

Index: chrome/common/extensions/permissions/chrome_api_permissions.cc
diff --git a/chrome/common/extensions/permissions/chrome_api_permissions.cc b/chrome/common/extensions/permissions/chrome_api_permissions.cc
index 81a3346b31c9e72f99d5b2d8295cc1a391e45089..e4f261965e87f4f50868358c28b1c91a27cf6849 100644
--- a/chrome/common/extensions/permissions/chrome_api_permissions.cc
+++ b/chrome/common/extensions/permissions/chrome_api_permissions.cc
@@ -109,6 +109,7 @@ std::vector<APIPermissionInfo*> ChromeAPIPermissions::GetAllPermissions()
        PermissionMessage::kContentSettings},
       {APIPermission::kContextMenus, "contextMenus"},
       {APIPermission::kCookie, "cookies"},
+      {APIPermission::kCopresence, "copresence"},

[not at google - send to devlin, 2014/08/07 20:41:19]

i can't remember the conclusion about an install warning, but I guess one wasn't
required?

[rkc, 2014/08/07 21:43:03]

Not for dev channel. Whitelisted apps will have their own privacy review and may
be required to show some sort of permissions dialog (considering we are
unauthenticated now, the privacy requires are somewhat relaxed).

The final install warning for this has not been decided yet, but before we open
the API up, it definitely will be.

[not at google - send to devlin, 2014/08/07 21:47:43]

I don't think that "it's dev channel" is a good reason to avoid an install
warning. And I'm not sure that the privacy implications are much different, an
extension can still figure out who you are through other APIs. Could you at
least make it "communicate with nearby devices" or something? anything?

[rkc, 2014/08/07 22:03:45]

Done.

       {APIPermission::kCopresencePrivate, "copresencePrivate"},
       {APIPermission::kEnterprisePlatformKeys, "enterprise.platformKeys"},
       {APIPermission::kFileBrowserHandler, "fileBrowserHandler",