Implement chrome://histograms with network service.

content/browser/histogram_internals_request_job.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_HISTOGRAM_INTERNALS_REQUEST_JOB_H_
 #define CONTENT_BROWSER_HISTOGRAM_INTERNALS_REQUEST_JOB_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "net/url_request/url_request_simple_job.h"
+#include "url/gurl.h"
 
 namespace content {
 
 class HistogramInternalsRequestJob : public net::URLRequestSimpleJob {
  public:
   HistogramInternalsRequestJob(net::URLRequest* request,
                                net::NetworkDelegate* network_delegate);
 
   // net::URLRequestSimpleJob:
   void Start() override;
   int GetData(std::string* mime_type,
               std::string* charset,
               std::string* data,
               const net::CompletionCallback& callback) const override;
 
+  // Generates the HTML for chrome://histograms. If |url| has a path, it's used
+  // to display a single histogram.
+  // base::StatisticsRecorder::ImportProvidedHistograms must have been called
+  // on the UI thread first.
+  static std::string GenerateHTML(const GURL& url);
+
  private:
   ~HistogramInternalsRequestJob() override;
 
   // Starts the real URL request.
   void StartUrlRequest();
 
-  // The string to select histograms which have |path_| as a substring.
-  std::string path_;
+  // The URL that was requested, which might have a path component to a specific
+  // histogram.
+  GURL url_;
 
   base::WeakPtrFactory<HistogramInternalsRequestJob> weak_factory_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(HistogramInternalsRequestJob);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_HISTOGRAM_INTERNALS_REQUEST_JOB_H_