Send all field trials from the browser.

chrome/renderer/chrome_render_process_observer.h

Index: chrome/renderer/chrome_render_process_observer.h
diff --git a/chrome/renderer/chrome_render_process_observer.h b/chrome/renderer/chrome_render_process_observer.h
index 75d8415e3997d53fade3b2cf2047456ffe085501..1c929704970ca54d26cdee0d882e1ce7186fdd77 100644
--- a/chrome/renderer/chrome_render_process_observer.h
+++ b/chrome/renderer/chrome_render_process_observer.h
@@ -10,6 +10,7 @@
 #include "base/compiler_specific.h"
 #include "base/files/file_path.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/metrics/field_trial.h"
 #include "components/content_settings/core/common/content_settings.h"
 #include "content/public/renderer/render_process_observer.h"
 
@@ -25,7 +26,8 @@ class ResourceDispatcherDelegate;
 // a RenderView) for Chrome specific messages that the content layer doesn't
 // happen.  If a few messages are related, they should probably have their own
 // observer.
-class ChromeRenderProcessObserver : public content::RenderProcessObserver {
+class ChromeRenderProcessObserver : public content::RenderProcessObserver,
+                                    public base::FieldTrialList::Observer {
  public:
   explicit ChromeRenderProcessObserver(
       ChromeContentRendererClient* client);
@@ -43,6 +45,10 @@ class ChromeRenderProcessObserver : public content::RenderProcessObserver {
   void WebKitInitialized() override;
   void OnRenderProcessShutdown() override;
 
+  // base::FieldTrialList::Observer implementation.

[Alexei Svitkine (slow), 2014/11/10 18:30:43]

Nit: New preferred wording for this comment is just:

// base::FieldTrialList::Observer:

Update the one above at the same time.

[Georges Khalil, 2014/11/10 19:22:29]

Done.

+  void OnFieldTrialGroupFinalized(const std::string& trial_name,
+                                  const std::string& group_name) override;
+
   void OnSetIsIncognitoProcess(bool is_incognito_process);
   void OnSetContentSettingsForCurrentURL(
       const GURL& url, const ContentSettings& content_settings);