Make field trials activated in the GPU process be reflected in browser.

chrome/renderer/chrome_render_thread_observer.h

Index: chrome/renderer/chrome_render_thread_observer.h
diff --git a/chrome/renderer/chrome_render_thread_observer.h b/chrome/renderer/chrome_render_thread_observer.h
index ed571ae98d8222d1430c8d70a2f2f5fe60e04525..d93aec0e0122f0c53f43af4813ec886f31eb9ab8 100644
--- a/chrome/renderer/chrome_render_thread_observer.h
+++ b/chrome/renderer/chrome_render_thread_observer.h
@@ -11,6 +11,7 @@
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
+#include "base/metrics/field_trial.h"
 #include "chrome/common/variations/child_process_field_trial_syncer.h"
 #include "components/content_settings/core/common/content_settings.h"
 #include "content/public/renderer/render_thread_observer.h"
@@ -30,7 +31,8 @@ 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 ChromeRenderThreadObserver : public content::RenderThreadObserver {
+class ChromeRenderThreadObserver : public content::RenderThreadObserver,
+                                   public base::FieldTrialList::Observer {
  public:
   ChromeRenderThreadObserver();
   ~ChromeRenderThreadObserver() override;
@@ -49,6 +51,10 @@ class ChromeRenderThreadObserver : public content::RenderThreadObserver {
   // content::RenderThreadObserver:
   bool OnControlMessageReceived(const IPC::Message& message) override;
 
+  // base::FieldTrialList::Observer:
+  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);