Don't compile code for desktop zoom or GuestViews on mobile platforms.

android_webview/browser/aw_browser_context.h

Index: android_webview/browser/aw_browser_context.h
diff --git a/android_webview/browser/aw_browser_context.h b/android_webview/browser/aw_browser_context.h
index c2a4bc251d1ff3743bd5b81a1438ccf842081681..26bcbcb4be1e9fc14dc3b3a070a993c966f3eb18 100644
--- a/android_webview/browser/aw_browser_context.h
+++ b/android_webview/browser/aw_browser_context.h
@@ -90,8 +90,6 @@ class AwBrowserContext : public content::BrowserContext,
   web_restrictions::WebRestrictionsClient* GetWebRestrictionProvider();
 
   // content::BrowserContext implementation.
-  std::unique_ptr<content::ZoomLevelDelegate> CreateZoomLevelDelegate(
-      const base::FilePath& partition_path) override;
   base::FilePath GetPath() const override;
   bool IsOffTheRecord() const override;
   content::ResourceContext* GetResourceContext() override;