predictors: Fix duplicate content type detection.

chrome/browser/predictors/resource_prefetch_predictor.h

Index: chrome/browser/predictors/resource_prefetch_predictor.h
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.h b/chrome/browser/predictors/resource_prefetch_predictor.h
index 15768ecf565f81f3dc87005b2053d29eea206b67..afad9b830432c9936f565ceec66b75f9a131abb7 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.h
+++ b/chrome/browser/predictors/resource_prefetch_predictor.h
@@ -91,6 +91,10 @@ class ResourcePrefetchPredictor
     std::string mime_type;
     bool was_cached;
     GURL redirect_url;  // Empty unless request was redirected to a valid url.
+
+    // Initializes a |URLRequestSummary| from a |URLRequest| response.
+    static bool SummarizeResponse(const net::URLRequest* request,

[pasko, 2016/08/09 17:08:54]

const net::URLRequest&

(yes, the const pointer is a majority, not sure why, it is against style guide,
here it is certainly not necessary to be a pointer)

[Benoit L, 2016/08/09 17:22:56]

Unfortunately, it is:
CONTENT_EXPORT static const ResourceRequestInfo* ForRequest(const
net::URLRequest* request);

[pasko, 2016/08/10 09:08:46]

Why would it be inconvenient to do the following?

content::ResourceRequestInfo::ForRequest(&request)

The content export is not beautiful, but let's try to make it easier to change
for better.

[Benoit L, 2016/08/10 14:08:47]

Done.

+                                  URLRequestSummary* summary);

[pasko, 2016/08/09 17:08:54]

Just returning a unique_ptr (instead of, ugh, output parameter) would make the
code more readable without comments and will make it easier to later remove the
evil default constructor for NavigationID.

Up to you for this small change, either to update the comment to say what this
function returns or to change the declaration.

[Benoit L, 2016/08/09 17:22:56]

The rest of the code uses URLRequestSummary by value, and output parameters are
common in Chrome.
Added a comment.

   };
 
   ResourcePrefetchPredictor(const ResourcePrefetchPredictorConfig& config,