Add support for transparent background API

chrome/common/extensions/api/_permission_features.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This features file defines permissions for extension APIs implemented
 // under src/chrome.
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 
 // To add a new whitelisted ID, SHA-1 it and force it to uppercase. In Bash:
@@ skipping 104 matching lines @@
         "40063F1CF7B68BA847A26FA6620DDF156171D23C",
         "A6FD8E15353CF1F5C3D0A7B20E1D10AEA4DD3E6A",
         "57AC4D9E6BD8A2D0A70056B5FAC2378CAA588912",
         "02037314DA4D913640DCF0E296A7D01F4FD793EC",
         "B6EC0809BC63E10B431C5E4AA3645232CA86B2A5",
         "48CA541313139786F056DBCB504A1025CFF5D2E3",
         "05106136AE7F08A3C181D4648E5438350B1D2B4F"
       ]
     }
   ],
+  "app.window.alpha": [
+    {
+      "channel": "beta",
+      "extension_types": ["platform_app"]
+    },
+    {
+      "channel": "stable",
+      "extension_types": ["platform_app"],
+      "whitelist": [
+        "0F42756099D914A026DADFA182871C015735DD95",  // http://crbug.com/323773

[benwells, 2014/08/05 23:37:05]

This feature is restricted to beta in code, so this whitelist won't do anything.

I don't think all these apps need it anyway.

[garykac, 2014/08/07 03:54:01]

Argh. It doesn't seem like we can restrict the permission with a whitelist here
and still provide a useful error message without duplicating the whitelist.

I'll update the code verify against the whitelist before returning the "channel"
error. But I'll do that tomorrow since I have to leave now.
I've remove the apps that only require shape.

+        "2D22CDB6583FD0A13758AEBE8B15E45208B4E9A7",
+        "E7E2461CE072DF036CF9592740196159E2D7C089",  // http://crbug.com/356200
+        "A74A4D44C7CFCD8844830E6140C8D763E12DD8F3",
+        "312745D9BF916161191143F6490085EEA0434997",
+        "53041A2FA309EECED01FFC751E7399186E860B2C",
+        "EBA908206905323CECE6DC4B276A58A0F4AC573F",
+        "2775E568AC98F9578791F1EAB65A1BF5F8CEF414",
+        "4AA3C5D69A4AECBD236CAD7884502209F0F5C169",
+        "E410CDAB2C6E6DD408D731016CECF2444000A912",
+        "9E930B2B5EABA6243AE6C710F126E54688E8FAF6",
+        "FAFE8EFDD2D6AE2EEB277AFEB91C870C79064D9E",  // http://crbug.com/327507
+        "3B52D273A271D4E2348233E322426DBAE854B567",
+        "5DF6ADC8708DF59FCFDDBF16AFBFB451380C2059",
+        "1037DEF5F6B06EA46153AD87B6C5C37440E3F2D1",
+        "F5815DAFEB8C53B078DD1853B2059E087C42F139",
+        "6A08EFFF9C16E090D6DCC7EC55A01CADAE840513",
+        "C32D6D93E12F5401DAA3A723E0C3CC5F25429BA4",  // http://crbug.com/354258
+        "9099782647D39C778E15C8C6E0D23C88F5CDE170",
+        "B7D5B52D1E5B106288BD7F278CAFA5E8D76108B0",
+        "89349DBAA2C4022FB244AA50182AB60934EB41EE",
+        "CB593E510640572A995CB1B6D41BD85ED51E63F8",
+        "1AD1AC86C87969CD3434FA08D99DBA6840AEA612",
+        "9C2EA21D7975BDF2B3C01C3A454EE44854067A6D",
+        "D2C488C80C3C90C3E01A991112A05E37831E17D0",
+        "6EEC061C0E74B46C7B5BE2EEFA49436368F4988F",
+        "8B344D9E8A4C505EF82A0DBBC25B8BD1F984E777",
+        "E06AFCB1EB0EFD237824CC4AC8FDD3D43E8BC868",
+        "F76F43EFFF56BF17A9868A5243F339BA28746632",  // http://crbug.com/386324
+        "C6EA52B92F80878515F94137020F01519357E5B5",
+        "E466389F058ABD73FF6FDD06F768A351FCBF8532",
+        "40063F1CF7B68BA847A26FA6620DDF156171D23C",
+        "A6FD8E15353CF1F5C3D0A7B20E1D10AEA4DD3E6A",
+        "57AC4D9E6BD8A2D0A70056B5FAC2378CAA588912",
+        "02037314DA4D913640DCF0E296A7D01F4FD793EC",
+        "B6EC0809BC63E10B431C5E4AA3645232CA86B2A5",
+        "48CA541313139786F056DBCB504A1025CFF5D2E3",
+        "05106136AE7F08A3C181D4648E5438350B1D2B4F"
+      ]
+    }
+  ],
   "audio": [
     {
       "channel": "dev",
       "extension_types": ["platform_app"]
     },
     {
       "channel": "stable",
       "extension_types": ["platform_app"],
       "whitelist": [
         "8C3741E3AF0B93B6E8E0DDD499BB0B74839EA578",
@@ skipping 982 matching lines @@
     // Only allowed for whitelisted extensions until all the caveats are
     // addressed. Tracked in crbug/285151.
     "channel": "stable",
     "extension_types": ["extension"],
     "location": "component",
     "whitelist": [
       "D519188F86D9ACCEE0412007B227D9936EB9676B"  // GAIA Component Extension
     ]
   }]
 }