Convert RapporRecorder to use mojo.

chrome/browser/chrome_content_browser_manifest_overlay.json

 {
   "name": "exe:content_browser",
   "capabilities": {
     "provided": {
       "renderer": [
         "autofill::mojom::AutofillDriver",
         "autofill::mojom::PasswordManagerDriver",
         "extensions::StashService",
         "metrics::mojom::LeakDetector",
+        "mojom::RapporRecorder",

[sky, 2016/10/06 17:28:44]

I don't think we want a top-level namespace named mojom, use a more specific
qualifier. chrome::mojom::RapporRecorder is fine.

[nigeltao1, 2016/10/07 03:30:51]

I was cargo-culting the other .mojom files under chrome/common, which are all
"mojom" and not "chrome::mojom". In contrast, .mojom files under content/common
are all "content::mojom". So says grep:

$ grep --no-filename ^module chrome/common/*.mojom
module mojom;
module mojom;
module mojom;
module mojom;
module mojom;
$ grep --no-filename ^module content/common/*.mojom
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;
module content.mojom;

But in any case, I'll move it into a component, so that it's "rappor::mojom",
similar to the existing "safe_json::mojom" defined by components/safe_json.

[sky, 2016/10/07 16:17:38]

I discussed the namespace issue with Ken the other day before sending this out
and he agreed a namespace should be used. So, I would assume these will change
with time too.

[nigeltao1, 2016/10/29 04:31:09]

OK, I sent out https://codereview.chromium.org/2465623002# to change one of
these from "module mojom" to "module chrome.mojom". If that goes well, I'll fix
the others as well.

         "startup_metric_utils::mojom::StartupMetricHost",
         "translate::mojom::ContentTranslateDriver"
       ],
       "gpu": [
         "metrics::mojom::CallStackProfileCollector"
       ],
       "ash": [
         "ash::mojom::SystemTray",
         "ash::mojom::SystemTrayClient"
       ]
     }
   }
 }