Move creation and ownership of HostZoomMap to content instead of having every embedder do this.

content/test/test_browser_context.cc

Index: content/test/test_browser_context.cc
===================================================================
--- content/test/test_browser_context.cc	(revision 122827)
+++ content/test/test_browser_context.cc	(working copy)
@@ -54,10 +54,6 @@
   return resource_context_.get();
 }
 
-HostZoomMap* TestBrowserContext::GetHostZoomMap() {
-  return NULL;
-}
-
 content::GeolocationPermissionContext*
 TestBrowserContext::GetGeolocationPermissionContext() {
   return NULL;