Add SetImageData api to chrome.clipboard.

chrome/common/extensions/api/_permission_features.json

Index: chrome/common/extensions/api/_permission_features.json
diff --git a/chrome/common/extensions/api/_permission_features.json b/chrome/common/extensions/api/_permission_features.json
index 37f368c827ec05e4dfbb538b4d257c3e0040ff8b..dc3219c2a8d67049f4d1f92ec5be6c5a78bf2fb3 100644
--- a/chrome/common/extensions/api/_permission_features.json
+++ b/chrome/common/extensions/api/_permission_features.json
@@ -150,6 +150,12 @@
       "extension", "legacy_packaged_app", "hosted_app", "platform_app"
     ]
   },
+  "clipboardReadWrite": {

[Devlin, 2016/11/16 02:34:33]

Why do we need this permission?

[jennyz, 2016/12/07 01:21:48]

This permission is need to showing the warning string for "accessing clipboard
data" at the installation time of the app/extension who use chrome.clipboard.

[Devlin, 2016/12/09 15:23:43]

But we have clipboardRead and clipboardWrite; can't we just require both of
those instead of making a new permission?

[Devlin, 2016/12/16 02:05:08]

This still wasn't answered, either?

[Devlin, 2016/12/20 21:25:02]

Again, this doesn't seem to have been answered.

[jennyz, 2016/12/20 22:16:53]

Yes, that was what I originally did. But UI designer does not like it since it
shows two separate strings instead one on the installation warning dialog, which
violates one of the guideline in "CRX API Security Checklist"
(https://docs.google.com/document/u/1/d/1RamP4-HJ7GAJY3yv2ju2cK50K9GhOsydJN6KI...)
as follows:

Collapse multiple warnings into a single warning when possible.[2]
Example: Combine “Read files” and “Write files” into “Read and write files”.

The string is provided by our UI designer. Therefore, I added this combined
permission instead of requiring clipboardRead and clipboardWrite.

[Devlin, 2016/12/21 23:58:38]

We should be able to solve that using permission rules.

[jennyz, 2016/12/22 22:45:20]

Removed this permission and changed to add a permission rule to associate the
string with both clipboardRead and clipboardWrite permission.

+    "channel": "dev",
+    "extension_types": [
+      "extension", "legacy_packaged_app", "hosted_app", "platform_app"
+    ]
+  },  
   "clipboardWrite": {
     "channel": "stable",
     "extension_types": [