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..733bfb912358ae3e72d79fa861b089547b9835bf 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);
@@ -51,6 +53,8 @@ class ChromeRenderProcessObserver : public content::RenderProcessObserver {
   void OnSetFieldTrialGroup(const std::string& fiel_trial_name,
                             const std::string& group_name);
   void OnGetV8HeapStats();
+  void OnFieldTrialGroupFinalized(const std::string& trial_name,

[Alexei Svitkine (slow), 2014/11/07 15:51:02]

This is implementing base::FieldTrialList::Observer, so actually please put this
in a separate section with the following comment above it:

// base::FieldTrialList::Observer:

I suggest put the section above the OnSetIsIncognitoProcess and separating it by
newlines between above and below it.

[Georges Khalil, 2014/11/07 16:44:23]

Done.

+                                  const std::string& group_name) override;
 
   static bool is_incognito_process_;
   scoped_ptr<content::ResourceDispatcherDelegate> resource_delegate_;