Convert SetVisuallyDeemphasized IPC to mojo

chrome/renderer/chrome_render_view_observer.h

Index: chrome/renderer/chrome_render_view_observer.h
diff --git a/chrome/renderer/chrome_render_view_observer.h b/chrome/renderer/chrome_render_view_observer.h
index f6473b06f8c5d3631e30555b8eec7be8b31b8438..ea76e9dc10a2c41d0515741eaaae7988a53826de 100644
--- a/chrome/renderer/chrome_render_view_observer.h
+++ b/chrome/renderer/chrome_render_view_observer.h
@@ -43,9 +43,6 @@ class ChromeRenderViewObserver : public content::RenderViewObserver {
 #if !defined(OS_ANDROID)
   void OnWebUIJavaScript(const base::string16& javascript);
 #endif
-#if BUILDFLAG(ENABLE_EXTENSIONS)
-  void OnSetVisuallyDeemphasized(bool deemphasized);
-#endif
 #if defined(OS_ANDROID)
   void OnUpdateBrowserControlsState(content::BrowserControlsState constraints,
                                     content::BrowserControlsState current,
@@ -63,9 +60,6 @@ class ChromeRenderViewObserver : public content::RenderViewObserver {
   // Owned by ChromeContentRendererClient and outlive us.
   web_cache::WebCacheImpl* web_cache_impl_;
 
-  // true if webview is overlayed with grey color.
-  bool webview_visually_deemphasized_;
-
   DISALLOW_COPY_AND_ASSIGN(ChromeRenderViewObserver);
 };