Introduce chrome.displaySource API

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index afee6e78eb832133d2cd2d330a552b3aba7e6cba..e0aa64e3990d8e4247dff64986c2ee4c6cbc561c 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -4215,6 +4215,9 @@ Even if you have downloaded files from this website before, the website might ha
         <message name="IDS_EXTENSION_PROMPT_WARNING_USERS_PRIVATE" desc="Permission string for access to user accounts.">
           Read and change whitelisted users
         </message>
+        <message name="IDS_EXTENSION_PROMPT_WARNING_DISPLAY_SOURCE" desc="Permission string for access to Display Source API.">
+          Manage Wi-Fi display connections

[asargent_no_longer_on_chrome, 2015/11/17 00:51:55]

I fear that this permission warning may not mean much to an ordinary user. I'd
imagine that even highly technical people who know a little about WiFi display
wouldn't get enough information from the word "manage".

Also, there was that thread of conversation in the design doc that ended with
the conclusion to rename the API namespace from "wifiDisplaySource to just
"displaySource". Should that same thing be reflected in this permission warning?


I think the kinds of questions that ordinary users might have about extensions
using this API are things like:

-Can this API be used by the extension to "see" what's on my screen? 
-Does the extension get to send media to any displays without my approval, or do
I get a chance to authorize it on every connection?

Would something like "Send audio and video to displays on the local network" be
both technically accurate and easier to understand?

[Mikhail, 2015/11/17 14:07:42]

Thanks for the proposal! I think it fits well.

+        </message>
       </if>
 
       <!-- Extension/App error messages -->