Revert of Revert CL 117933003. Re-add resource speculative prefetching code.

chrome/browser/net/resource_prefetch_predictor_observer.cc

Index: chrome/browser/net/resource_prefetch_predictor_observer.cc
diff --git a/chrome/browser/net/resource_prefetch_predictor_observer.cc b/chrome/browser/net/resource_prefetch_predictor_observer.cc
deleted file mode 100644
index 5a3f4a1979b09d4163e546bafd4dfb910e94771f..0000000000000000000000000000000000000000
--- a/chrome/browser/net/resource_prefetch_predictor_observer.cc
+++ /dev/null
@@ -1,202 +0,0 @@
-// Copyright 2014 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.
-
-#include "chrome/browser/net/resource_prefetch_predictor_observer.h"
-
-#include <string>
-
-#include "base/metrics/histogram.h"
-#include "content/public/browser/browser_thread.h"
-#include "content/public/browser/render_frame_host.h"
-#include "content/public/browser/resource_request_info.h"
-#include "net/url_request/url_request.h"
-#include "url/gurl.h"
-
-using content::BrowserThread;
-using predictors::ResourcePrefetchPredictor;
-
-namespace {
-
-// Enum for measuring statistics pertaining to observed request, responses and
-// redirects.
-enum RequestStats {
-  REQUEST_STATS_TOTAL_RESPONSES = 0,
-  REQUEST_STATS_TOTAL_PROCESSED_RESPONSES = 1,
-  REQUEST_STATS_NO_RESOURCE_REQUEST_INFO = 2,
-  REQUEST_STATS_NO_RENDER_FRAME_ID_FROM_REQUEST_INFO = 3,
-  REQUEST_STATS_MAX = 4,
-};
-
-// Specific to main frame requests.
-enum MainFrameRequestStats {
-  MAIN_FRAME_REQUEST_STATS_TOTAL_REQUESTS = 0,
-  MAIN_FRAME_REQUEST_STATS_PROCESSED_REQUESTS = 1,
-  MAIN_FRAME_REQUEST_STATS_TOTAL_REDIRECTS = 2,
-  MAIN_FRAME_REQUEST_STATS_PROCESSED_REDIRECTS = 3,
-  MAIN_FRAME_REQUEST_STATS_TOTAL_RESPONSES = 4,
-  MAIN_FRAME_REQUEST_STATS_PROCESSED_RESPONSES = 5,
-  MAIN_FRAME_REQUEST_STATS_MAX = 6,
-};
-
-void ReportRequestStats(RequestStats stat) {
-  UMA_HISTOGRAM_ENUMERATION("ResourcePrefetchPredictor.RequestStats",
-                            stat,
-                            REQUEST_STATS_MAX);
-}
-
-void ReportMainFrameRequestStats(MainFrameRequestStats stat) {
-  UMA_HISTOGRAM_ENUMERATION("ResourcePrefetchPredictor.MainFrameRequestStats",
-                            stat,
-                            MAIN_FRAME_REQUEST_STATS_MAX);
-}
-
-bool SummarizeResponse(net::URLRequest* request,
-                       ResourcePrefetchPredictor::URLRequestSummary* summary) {
-  const content::ResourceRequestInfo* info =
-      content::ResourceRequestInfo::ForRequest(request);
-  if (!info) {
-    ReportRequestStats(REQUEST_STATS_NO_RESOURCE_REQUEST_INFO);
-    return false;
-  }
-
-  int render_process_id, render_frame_id;
-  if (!info->GetAssociatedRenderFrame(&render_process_id, &render_frame_id)) {
-    ReportRequestStats(REQUEST_STATS_NO_RENDER_FRAME_ID_FROM_REQUEST_INFO);
-    return false;
-  }
-
-  summary->navigation_id.render_process_id = render_process_id;
-  summary->navigation_id.render_frame_id = render_frame_id;
-  summary->navigation_id.main_frame_url = request->first_party_for_cookies();
-  summary->navigation_id.creation_time = request->creation_time();
-  summary->resource_url = request->original_url();
-  summary->resource_type = info->GetResourceType();
-  request->GetMimeType(&summary->mime_type);
-  summary->was_cached = request->was_cached();
-
-  // Use the mime_type to determine the resource type for subresources since
-  // types such as PREFETCH, SUB_RESOURCE, etc are not useful.
-  if (summary->resource_type != content::RESOURCE_TYPE_MAIN_FRAME) {
-    summary->resource_type =
-        ResourcePrefetchPredictor::GetResourceTypeFromMimeType(
-            summary->mime_type,
-            summary->resource_type);
-  }
-  return true;
-}
-
-}  // namespace
-
-namespace chrome_browser_net {
-
-ResourcePrefetchPredictorObserver::ResourcePrefetchPredictorObserver(
-    ResourcePrefetchPredictor* predictor)
-    : predictor_(predictor->AsWeakPtr()) {
-  DCHECK_CURRENTLY_ON(BrowserThread::UI);
-}
-
-ResourcePrefetchPredictorObserver::~ResourcePrefetchPredictorObserver() {
-  CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI) ||
-        BrowserThread::CurrentlyOn(BrowserThread::IO));
-}
-
-void ResourcePrefetchPredictorObserver::OnRequestStarted(
-    net::URLRequest* request,
-    content::ResourceType resource_type,
-    int child_id,
-    int frame_id) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME)
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_TOTAL_REQUESTS);
-
-  if (!ResourcePrefetchPredictor::ShouldRecordRequest(request, resource_type))
-    return;
-
-  ResourcePrefetchPredictor::URLRequestSummary summary;
-  summary.navigation_id.render_process_id = child_id;
-  summary.navigation_id.render_frame_id = frame_id;
-  summary.navigation_id.main_frame_url = request->first_party_for_cookies();
-  summary.resource_url = request->original_url();
-  summary.resource_type = resource_type;
-
-  BrowserThread::PostTask(
-      BrowserThread::UI,
-      FROM_HERE,
-      base::Bind(&ResourcePrefetchPredictor::RecordURLRequest,
-                 predictor_,
-                 summary));
-
-  if (resource_type == content::RESOURCE_TYPE_MAIN_FRAME)
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_PROCESSED_REQUESTS);
-}
-
-void ResourcePrefetchPredictorObserver::OnRequestRedirected(
-    const GURL& redirect_url,
-    net::URLRequest* request) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  const content::ResourceRequestInfo* request_info =
-      content::ResourceRequestInfo::ForRequest(request);
-  if (request_info &&
-      request_info->GetResourceType() == content::RESOURCE_TYPE_MAIN_FRAME) {
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_TOTAL_REDIRECTS);
-  }
-
-  if (!ResourcePrefetchPredictor::ShouldRecordRedirect(request))
-    return;
-
-  ResourcePrefetchPredictor::URLRequestSummary summary;
-  if (!SummarizeResponse(request, &summary))
-    return;
-
-  summary.redirect_url = redirect_url;
-
-  BrowserThread::PostTask(
-      BrowserThread::UI,
-      FROM_HERE,
-      base::Bind(&ResourcePrefetchPredictor::RecordURLRedirect,
-                 predictor_,
-                 summary));
-
-  if (request_info &&
-      request_info->GetResourceType() == content::RESOURCE_TYPE_MAIN_FRAME) {
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_PROCESSED_REDIRECTS);
-  }
-}
-
-void ResourcePrefetchPredictorObserver::OnResponseStarted(
-    net::URLRequest* request) {
-  DCHECK_CURRENTLY_ON(BrowserThread::IO);
-
-  ReportRequestStats(REQUEST_STATS_TOTAL_RESPONSES);
-
-  const content::ResourceRequestInfo* request_info =
-      content::ResourceRequestInfo::ForRequest(request);
-  if (request_info &&
-      request_info->GetResourceType() == content::RESOURCE_TYPE_MAIN_FRAME) {
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_TOTAL_RESPONSES);
-  }
-
-  if (!ResourcePrefetchPredictor::ShouldRecordResponse(request))
-    return;
-  ResourcePrefetchPredictor::URLRequestSummary summary;
-  if (!SummarizeResponse(request, &summary))
-    return;
-
-  BrowserThread::PostTask(
-      BrowserThread::UI,
-      FROM_HERE,
-      base::Bind(&ResourcePrefetchPredictor::RecordURLResponse,
-                 predictor_,
-                 summary));
-
-  ReportRequestStats(REQUEST_STATS_TOTAL_PROCESSED_RESPONSES);
-  if (request_info &&
-      request_info->GetResourceType() == content::RESOURCE_TYPE_MAIN_FRAME) {
-    ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_PROCESSED_RESPONSES);
-  }
-}
-
-}  // namespace chrome_browser_net