Remove EPM:all_hosts_ and use all_extension_views_ instead.

chrome/browser/renderer_host/chrome_render_view_host_observer.h

Index: chrome/browser/renderer_host/chrome_render_view_host_observer.h
diff --git a/chrome/browser/renderer_host/chrome_render_view_host_observer.h b/chrome/browser/renderer_host/chrome_render_view_host_observer.h
index 3d43e53d1ba3051e5afd2e9aa81b3ed1720d4599..690c31fc9c22b6a4990f3937719fdb3fd4d2b667 100644
--- a/chrome/browser/renderer_host/chrome_render_view_host_observer.h
+++ b/chrome/browser/renderer_host/chrome_render_view_host_observer.h
@@ -12,6 +12,10 @@ namespace chrome_browser_net {
 class Predictor;
 }
 
+namespace content {
+class WebContents;
+}
+
 class Extension;
 class Profile;
 
@@ -40,6 +44,8 @@ class ChromeRenderViewHostObserver : public content::RenderViewHostObserver {
   const Extension* GetExtension();
   // Cleans up when a RenderViewHost is removed, or on destruction.
   void RemoveRenderViewHostForExtensions(content::RenderViewHost* rvh);
+  // Retrieves the WebContents for a RenderViewHost.
+  content::WebContents* GetWebContents(content::RenderViewHost* rvh);
   void OnFocusedEditableNodeTouched();
 
   Profile* profile_;