[PresentationAPI, Android] Add ChromeMediaRouterDialogController.java and bind it with the native M…

chrome/browser/media/android/router/media_router_dialog_controller_android.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/media/android/router/media_router_dialog_controller_android.h"
 
+#include "base/android/jni_android.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_delegate.h"
+#include "jni/ChromeMediaRouterDialogController_jni.h"
 
 DEFINE_WEB_CONTENTS_USER_DATA_KEY(
     media_router::MediaRouterDialogControllerAndroid);
 
 using content::WebContents;
 
 namespace media_router {
 
 // static
 MediaRouterDialogControllerAndroid*
 MediaRouterDialogControllerAndroid::GetOrCreateForWebContents(
     WebContents* web_contents) {
   DCHECK(web_contents);
   // This call does nothing if the controller already exists.
   MediaRouterDialogControllerAndroid::CreateForWebContents(web_contents);
   return MediaRouterDialogControllerAndroid::FromWebContents(web_contents);
 }
 
 MediaRouterDialogControllerAndroid::MediaRouterDialogControllerAndroid(
     WebContents* web_contents)
     : MediaRouterDialogController(web_contents) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  CHECK(env);

[Bernhard Bauer, 2015/08/06 15:23:01]

Is this CHECK actually necessary? I would only expect this to fail under very
exceptional circumstances, and then you'd presumably crash anyway.

[whywhat, 2015/08/06 15:27:13]

I'd think in such exceptional circumstances one should crash earlier than later.
IIRC it's the common thing to do after acquiring |env| in Chromium. Have this
practice changed?

[Bernhard Bauer, 2015/08/06 15:40:33]

I have never seen it, TBH. If anything, we should check directly in
AttachCurrentThread(), and we usually do DCHECKs for these sorts of things
(CHECKs are mostly used to turn an otherwise unclean memory access into a clean
crash, for security reasons, but dereferencing a null pointer is okay). And
looking at AttachCurrentThread(), there is already a DCHECK for the result of
JavaVM::AttachCurrentThread().

[whywhat, 2015/08/06 16:29:20]

Ok, CHECK removed.

+  java_dialog_controller_.Reset(Java_ChromeMediaRouterDialogController_create(
+      env,
+      reinterpret_cast<intptr_t>(this),
+      base::android::GetApplicationContext()));
+}
+
+// static
+bool MediaRouterDialogControllerAndroid::Register(JNIEnv* env) {
+  bool ret = RegisterNativesImpl(env);
+  DCHECK(g_ChromeMediaRouterDialogController_clazz);
+  return ret;
 }
 
 MediaRouterDialogControllerAndroid::~MediaRouterDialogControllerAndroid() {
 }
 
 void MediaRouterDialogControllerAndroid::CreateMediaRouterDialog() {
   NOTIMPLEMENTED();
 }
 
 void MediaRouterDialogControllerAndroid::CloseMediaRouterDialog() {
   NOTIMPLEMENTED();
 }
 
 bool MediaRouterDialogControllerAndroid::IsShowingMediaRouterDialog() const {
   NOTIMPLEMENTED();
   return false;
 }
 
 }  // namespace media_router