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

chrome/browser/net/resource_prefetch_predictor_observer.cc

+// 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