Add PluginInstaller to encapsulate information about a missing plug-in.

chrome/browser/resources/plugins_mac.json

 {
   "plugins": [
     {
       "mime_types": [
         "application/x-java-applet",
         "application/x-java-applet,version=1.1",
         "application/x-java-applet,version=1.1.1",
         "application/x-java-applet,version=1.1.2",
         "application/x-java-applet,version=1.1.3",
         "application/x-java-applet,version=1.2",
@@ skipping 18 matching lines @@
         "application/x-java-bean,version=1.3.1",
         "application/x-java-bean,version=1.4",
         "application/x-java-bean,version=1.4.1",
         "application/x-java-bean,version=1.4.2",
         "application/x-java-bean,version=1.5",
         "application/x-java-bean,version=1.6",
         "application/x-java-vm"
       ],
       "lang": "en-US",
       "name": "Java(TM)",
+      "identifier": "java-runtime-environment",
       "url": "http://java.com/en/download/apple_manual.jsp",
       "displayurl": true
     },
     {
       "mime_types": [
         "audio/vnd.rn-realaudio",
         "video/vnd.rn-realvideo",
         "audio/x-pn-realaudio-plugin",
         "audio/x-pn-realaudio"
       ],
       "lang": "en-US",
       "name": "RealPlayer",
+      "identifier": "realplayer",
       "url": "http://www.real.com/realplayer/download",
       "displayurl": true
     },
     {
       "mime_types": [
         "application/futuresplash",
         "application/x-shockwave-flash"
       ],
       "lang": "en-US",
       "name": "Adobe Flash Player",
+      "identifier": "adobe-flash-player",
       "url": "http://get.adobe.com/flashplayer/",
       "displayurl": true
     },
     {
       "mime_types": [
         "application/x-director"
       ],
       "lang": "en-US",
       "name": "Adobe Shockwave Player",
+      "identifier": "shockwave",
       "url": "http://www.adobe.com/shockwave/download/",
       "displayurl": true
     },
     {
       "mime_types": [
         "application/pdf",
         "application/vnd.adobe.x-mars",
         "application/vnd.adobe.xdp+xml",
         "application/vnd.adobe.xfd+xml",
         "application/vnd.adobe.xfdf",
         "application/vnd.fdf"
       ],
       "lang": "en-US",
       "name": "Adobe Reader",
+      "identifier": "adobe-reader",
       "url": "http://get.adobe.com/reader/",
       "displayurl": true
     },
     {
       "mime_types": [
         "application/sdp",
         "application/x-mpeg",
         "application/x-rtsp",
         "application/x-sdp",
         "audio/3ggp",
@@ skipping 37 matching lines @@
         "video/flc",
         "video/mp4",
         "video/mpeg",
         "video/quicktime",
         "video/sd-video",
         "video/x-m4v",
         "video/x-mpeg"
       ],
       "lang": "en-US",
       "name": "QuickTime Player",
+      "identifier": "apple-quicktime",
       "url": "http://www.apple.com/quicktime/download/",
       "displayurl": true
     },
     {
       "mime_types": [
         "application/asx",
         "application/x-mplayer2",
         "application/x-ms-wmp",
         "audio/x-ms-wax",
         "audio/x-ms-wma",
         "video/x-ms-asf",
         "video/x-ms-asf-plugin",
         "video/x-ms-wm",
         "video/x-ms-wmv",
         "video/x-ms-wvx"
       ],
       "lang": "en-US",
       "name": "Flip4Mac",
+      "identifier": "flip4mac",
       "url": "http://www.telestream.net/flip4mac-wmv/overview.htm",
       "displayurl": true
     },
     {
       "mime_types": [
         "video/divx",
         "video/x-matroska"
       ],
       "lang": "en-US",
       "name": "DivX Web Player",
+      "identifier": "divx-player",
       "url": "http://www.divx.com/en/downloads/divx/mac",
       "displayurl": true
     }
   ]
 }