Use GPU blacklist to control accelerated video decode.

chrome/browser/resources/software_rendering_list.json

Index: chrome/browser/resources/software_rendering_list.json
===================================================================
--- chrome/browser/resources/software_rendering_list.json	(revision 151736)
+++ chrome/browser/resources/software_rendering_list.json	(working copy)
@@ -37,7 +37,7 @@
 // 16. "blacklist" is a list of gpu feature strings, valid values include
 //     "accelerated_2d_canvas", "accelerated_compositing", "webgl",
 //     "multisampling", "flash_3d", "flash_stage3d", "texture_sharing",
-//     and "all".
+//     "accelerated_video_decode", and "all".
 //     This field is mandatory.
 // 17. "description" has the description of the entry.
 // 18. "webkit_bugs" is an array of associated webkit bug numbers.
@@ -68,7 +68,7 @@
 {
   "name": "software rendering list",
   // Please update the version number whenever you change this file.
-  "version": "2.8",
+  "version": "2.9",
   "entries": [
     {
       "id": 1,
@@ -665,6 +665,21 @@
       "blacklist": [
         "all"
       ]
+    },
+    {
+      "id": 48,
+      "description": "Accelerated video decode is unstable except for ChromeOS",

[Ami GONE FROM CHROMIUM, 2012/08/17 00:19:17]

This isn't accurate.  The 142402 disablement was a speculative step, and appears
*not* to have been to blame, after all.  We're on track for shipping hw decode
on m22 to windows.
Assuming we ship there then this string just wants to be:
Accelerated video decode is unavailable on Mac and Linux

[Zhenyao Mo, 2012/08/17 00:25:09]

Will change.

+      "cr_bugs": [137247, 142402],
+      "exceptions": [
+        {
+          "os": {
+            "type": "chromeos"

[Ami GONE FROM CHROMIUM, 2012/08/17 00:19:17]

I guess add "win" here?

[Zhenyao Mo, 2012/08/17 00:25:09]

The windows is not on at the moment, are you sure about turning it on?  If yes,
I can add win here.

[Ami GONE FROM CHROMIUM, 2012/08/17 04:14:00]

I'm currently negotiating that, and it looks like I'll reenable on win tomorrow
morning, hopefully before this CL lands (to make the revert clearest).  

+          }
+        }
+      ],
+      "blacklist": [
+        "accelerated_video_decode"
+      ]
     }
   ]
 }