X-Chrome-Variations logic refactoring

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
index fb6e707047efaab34e74c40a4005edac0bfc58d2..ecc8b37564d8ff6e7e34aa800e39b365c4379d77 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -9,6 +9,7 @@
 #include "base/base64.h"
 #include "base/logging.h"
 #include "chrome/browser/browser_process.h"
+#include "chrome/browser/chrome_metrics_helper.h"
 #include "chrome/browser/content_settings/host_content_settings_map.h"
 #include "chrome/browser/download/download_request_limiter.h"
 #include "chrome/browser/download/download_resource_throttle.h"
@@ -30,8 +31,6 @@
 #include "chrome/common/chrome_notification_types.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/extensions/user_script.h"
-#include "chrome/common/metrics/variations/variations_util.h"
-#include "chrome/common/metrics/proto/chrome_experiments.pb.h"
 #include "chrome/common/render_messages.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/notification_service.h"
@@ -87,8 +86,7 @@ ChromeResourceDispatcherHostDelegate::ChromeResourceDispatcherHostDelegate(
     : download_request_limiter_(g_browser_process->download_request_limiter()),
       safe_browsing_(g_browser_process->safe_browsing_service()),
       user_script_listener_(new extensions::UserScriptListener()),
-      prerender_tracker_(prerender_tracker),
-      variation_ids_cache_initialized_(false) {
+      prerender_tracker_(prerender_tracker) {
 }
 
 ChromeResourceDispatcherHostDelegate::~ChromeResourceDispatcherHostDelegate() {
@@ -164,7 +162,19 @@ void ChromeResourceDispatcherHostDelegate::RequestBeginning(
   }
 #endif
 
-  AppendChromeMetricsHeaders(request, resource_context, resource_type);
+  // Don't attempt to append headers to requests that have already started.
+  // TODO(stevet): Remove this once the request ordering issues are resolved
+  // in crbug.com/128048.
+  if (!request->is_pending()) {
+    net::HttpRequestHeaders headers;
+    headers.CopyFrom(request->extra_request_headers());
+    ProfileIOData* io_data = ProfileIOData::FromResourceContext(
+        resource_context);
+    ChromeMetricsHelper::GetInstance()->AppendHeaders(
+        request->url(), io_data->is_incognito(),
+        io_data->GetMetricsEnabledStateOnIOThread(), &headers);
+    request->SetExtraRequestHeaders(headers);
+  }
 
 #if defined(ENABLE_ONE_CLICK_SIGNIN)
   AppendChromeSyncGaiaHeader(request, resource_context);
@@ -312,45 +322,6 @@ void ChromeResourceDispatcherHostDelegate::AppendStandardResourceThrottles(
     throttles->push_back(throttle);
 }
 
-void ChromeResourceDispatcherHostDelegate::AppendChromeMetricsHeaders(
-    net::URLRequest* request,
-    content::ResourceContext* resource_context,
-    ResourceType::Type resource_type) {
-  // Don't attempt to append headers to requests that have already started.
-  // TODO(stevet): Remove this once the request ordering issues are resolved
-  // in crbug.com/128048.
-  if (request->is_pending())
-    return;
-
-  // Note the criteria for attaching Chrome experiment headers:
-  // 1. We only transmit to *.google.<TLD> domains. NOTE that this use of
-  //    google_util helpers to check this does not guarantee that the URL is
-  //    Google-owned, only that it is of the form *.google.<TLD>. In the future
-  //    we may choose to reinforce this check.
-  // 2. Only transmit for non-Incognito profiles.
-  // 3. For the X-Chrome-UMA-Enabled bit, only set it if UMA is in fact enabled
-  //    for this install of Chrome.
-  // 4. For the X-Chrome-Variations, only include non-empty variation IDs.
-  ProfileIOData* io_data = ProfileIOData::FromResourceContext(resource_context);
-  if (io_data->is_incognito() ||
-      !google_util::IsGoogleDomainUrl(request->url().spec(),
-                                      google_util::ALLOW_SUBDOMAIN,
-                                      google_util::ALLOW_NON_STANDARD_PORTS))
-    return;
-
-  if (io_data->GetMetricsEnabledStateOnIOThread())
-    request->SetExtraRequestHeaderByName("X-Chrome-UMA-Enabled", "1", false);
-
-  // Lazily initialize the header, if not already done, before attempting to
-  // transmit it.
-  InitVariationIDsCacheIfNeeded();
-  if (!variation_ids_header_.empty()) {
-    request->SetExtraRequestHeaderByName("X-Chrome-Variations",
-        variation_ids_header_,
-        false);
-  }
-}
-
 #if defined(ENABLE_ONE_CLICK_SIGNIN)
 void ChromeResourceDispatcherHostDelegate::AppendChromeSyncGaiaHeader(
     net::URLRequest* request,
@@ -458,76 +429,3 @@ void ChromeResourceDispatcherHostDelegate::OnRequestRedirected(
         redirect_url, request);
   }
 }
-
-void ChromeResourceDispatcherHostDelegate::OnFieldTrialGroupFinalized(
-    const std::string& trial_name,
-    const std::string& group_name) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  chrome_variations::VariationID new_id =
-      chrome_variations::GetGoogleVariationID(
-          chrome_variations::GOOGLE_WEB_PROPERTIES, trial_name, group_name);
-  if (new_id == chrome_variations::kEmptyID)
-    return;
-  variation_ids_set_.insert(new_id);
-  UpdateVariationIDsHeaderValue();
-}
-
-void ChromeResourceDispatcherHostDelegate::InitVariationIDsCacheIfNeeded() {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  if (variation_ids_cache_initialized_)
-    return;
-
-  // Register for additional cache updates. This is done first to avoid a race
-  // that could cause registered FieldTrials to be missed.
-  base::FieldTrialList::AddObserver(this);
-
-  base::FieldTrial::ActiveGroups initial_groups;
-  base::FieldTrialList::GetActiveFieldTrialGroups(&initial_groups);
-  for (base::FieldTrial::ActiveGroups::const_iterator it =
-       initial_groups.begin(); it != initial_groups.end(); ++it) {
-    const chrome_variations::VariationID id =
-        chrome_variations::GetGoogleVariationID(
-            chrome_variations::GOOGLE_WEB_PROPERTIES, it->trial_name,
-            it->group_name);
-    if (id != chrome_variations::kEmptyID)
-      variation_ids_set_.insert(id);
-  }
-  UpdateVariationIDsHeaderValue();
-
-  variation_ids_cache_initialized_ = true;
-}
-
-void ChromeResourceDispatcherHostDelegate::UpdateVariationIDsHeaderValue() {
-  // The header value is a serialized protobuffer of Variation IDs which is
-  // base64 encoded before transmitting as a string.
-  if (variation_ids_set_.empty())
-    return;
-
-  // This is the bottleneck for the creation of the header, so validate the size
-  // here. Force a hard maximum on the ID count in case the Variations server
-  // returns too many IDs and DOSs receiving servers with large requests.
-  DCHECK_LE(variation_ids_set_.size(), 10U);
-  if (variation_ids_set_.size() > 20) {
-    variation_ids_header_.clear();
-    return;
-  }
-
-  metrics::ChromeVariations proto;
-  for (std::set<chrome_variations::VariationID>::const_iterator it =
-      variation_ids_set_.begin(); it != variation_ids_set_.end(); ++it)
-    proto.add_variation_id(*it);
-
-  std::string serialized;
-  proto.SerializeToString(&serialized);
-
-  std::string hashed;
-  if (base::Base64Encode(serialized, &hashed)) {
-    // If successful, swap the header value with the new one.
-    // Note that the list of IDs and the header could be temporarily out of sync
-    // if IDs are added as the header is recreated. The receiving servers are OK
-    // with such descrepancies.
-    variation_ids_header_ = hashed;
-  } else {
-    DVLOG(1) << "Failed to base64 encode Variation IDs value: " << serialized;
-  }
-}