Standardize usage of virtual/override/final in content/

This patch was automatically generated by applying clang fixit hints
generated by the plugin to the source tree.

BUG=417463
[email protected]

Review URL: https://codereview.chromium.org/671663002

Cr-Commit-Position: refs/heads/master@{#300461}
diff --git a/content/test/test_render_frame_host.h b/content/test/test_render_frame_host.h
index 025371f..506f1d4 100644
--- a/content/test/test_render_frame_host.h
+++ b/content/test/test_render_frame_host.h
@@ -21,10 +21,10 @@
 class TestRenderFrameHostCreationObserver : public WebContentsObserver {
  public:
   explicit TestRenderFrameHostCreationObserver(WebContents* web_contents);
-  virtual ~TestRenderFrameHostCreationObserver();
+  ~TestRenderFrameHostCreationObserver() override;
 
   // WebContentsObserver implementation.
-  virtual void RenderFrameCreated(RenderFrameHost* render_frame_host) override;
+  void RenderFrameCreated(RenderFrameHost* render_frame_host) override;
 
   RenderFrameHost* last_created_frame() const { return last_created_frame_; }
 
@@ -41,23 +41,21 @@
                       FrameTreeNode* frame_tree_node,
                       int routing_id,
                       bool is_swapped_out);
-  virtual ~TestRenderFrameHost();
+  ~TestRenderFrameHost() override;
 
   // RenderFrameHostImpl overrides (same values, but in Test* types)
-  virtual TestRenderViewHost* GetRenderViewHost() override;
+  TestRenderViewHost* GetRenderViewHost() override;
 
   // RenderFrameHostTester implementation.
-  virtual TestRenderFrameHost* AppendChild(
-      const std::string& frame_name) override;
-  virtual void SendNavigate(int page_id, const GURL& url) override;
-  virtual void SendFailedNavigate(int page_id, const GURL& url) override;
-  virtual void SendNavigateWithTransition(
-      int page_id,
-      const GURL& url,
-      ui::PageTransition transition) override;
-  virtual void SetContentsMimeType(const std::string& mime_type) override;
-  virtual void SendBeforeUnloadACK(bool proceed) override;
-  virtual void SimulateSwapOutACK() override;
+  TestRenderFrameHost* AppendChild(const std::string& frame_name) override;
+  void SendNavigate(int page_id, const GURL& url) override;
+  void SendFailedNavigate(int page_id, const GURL& url) override;
+  void SendNavigateWithTransition(int page_id,
+                                  const GURL& url,
+                                  ui::PageTransition transition) override;
+  void SetContentsMimeType(const std::string& mime_type) override;
+  void SendBeforeUnloadACK(bool proceed) override;
+  void SimulateSwapOutACK() override;
 
   void SendNavigateWithTransitionAndResponseCode(
       int page_id,