Chromecast: use CastContent{Browser,Renderer}Client as a base class.

This will allow consolidating many current "link-time" implementations
into virtual methods in our ContentClient classes, which should both
provide increased clarity and eliminate frequent internal build breaks
due to lag between a new public feature and matching internal CLs.

See discussion on https://codereview.chromium.org/1168643004/.

R=halliwell@chromium.org,lcwu@chromium.org,byungchul@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/1153173006

Cr-Commit-Position: refs/heads/master@{#333151}

chromecast/app/cast_main_delegate.cc

@@ -150,13 +150,13 @@ void CastMainDelegate::InitializeResourceBundle() {
 }
 
 content::ContentBrowserClient* CastMainDelegate::CreateContentBrowserClient() {
-  browser_client_.reset(new CastContentBrowserClient);
+  browser_client_ = CastContentBrowserClient::Create();
   return browser_client_.get();
 }
 
 content::ContentRendererClient*
 CastMainDelegate::CreateContentRendererClient() {
-  renderer_client_.reset(new CastContentRendererClient);
+  renderer_client_ = CastContentRendererClient::Create();
   return renderer_client_.get();
 }
 

chromecast/browser/cast_content_browser_client.h

@@ -42,7 +42,10 @@ class URLRequestContextFactory;
 
 class CastContentBrowserClient: public content::ContentBrowserClient {
  public:
-  CastContentBrowserClient();
+  // Creates an implementation of CastContentBrowserClient. Platform should
+  // link in an implementation as needed.
+  static scoped_ptr<CastContentBrowserClient> Create();
+
   ~CastContentBrowserClient() override;
 
   // Appends extra command line arguments before launching a new process.
@@ -119,6 +122,9 @@ class CastContentBrowserClient: public content::ContentBrowserClient {
       content::WebContents* web_contents) override;
 #endif  // defined(OS_ANDROID) && defined(VIDEO_HOLE)
 
+ protected:
+  CastContentBrowserClient();
+
  private:
   void AddNetworkHintsMessageFilter(int render_process_id,
                                     net::URLRequestContext* context);

chromecast/browser/cast_content_browser_client_simple.cc

@@ -4,6 +4,7 @@
 
 #include "chromecast/browser/cast_content_browser_client.h"
 
+#include "base/memory/scoped_ptr.h"
 #include "chromecast/media/cma/backend/media_pipeline_device.h"
 #include "content/public/browser/browser_message_filter.h"
 #include "media/audio/audio_manager_factory.h"
@@ -11,6 +12,11 @@
 namespace chromecast {
 namespace shell {
 
+// static
+scoped_ptr<CastContentBrowserClient> CastContentBrowserClient::Create() {
+  return make_scoped_ptr(new CastContentBrowserClient());
+}
+
 void CastContentBrowserClient::PlatformAppendExtraCommandLineSwitches(
     base::CommandLine* command_line) {
 }

chromecast/renderer/cast_content_renderer_client.h

@@ -27,7 +27,10 @@ void PlatformAddRendererNativeBindings(blink::WebLocalFrame* frame);
 
 class CastContentRendererClient : public content::ContentRendererClient {
  public:
-  CastContentRendererClient();
+  // Creates an implementation of CastContentRendererClient. Platform should
+  // link in an implementation as needed.
+  static scoped_ptr<CastContentRendererClient> Create();
+
   ~CastContentRendererClient() override;
 
   // Returns any MessageFilters from the platform implementation that should
@@ -49,6 +52,9 @@ class CastContentRendererClient : public content::ContentRendererClient {
   void DeferMediaLoad(content::RenderFrame* render_frame,
                       const base::Closure& closure) override;
 
+ protected:
+  CastContentRendererClient();
+
  private:
   scoped_ptr<network_hints::PrescientNetworkingDispatcher>
       prescient_networking_dispatcher_;

chromecast/renderer/cast_content_renderer_client_simple.cc

@@ -4,11 +4,17 @@
 
 #include "chromecast/renderer/cast_content_renderer_client.h"
 
+#include "base/memory/scoped_ptr.h"
 #include "ipc/message_filter.h"
 
 namespace chromecast {
 namespace shell {
 
+// static
+scoped_ptr<CastContentRendererClient> CastContentRendererClient::Create() {
+  return make_scoped_ptr(new CastContentRendererClient());
+}
+
 void PlatformAddRendererNativeBindings(blink::WebLocalFrame* frame) {
 }