Implement SmartText selection.

content/browser/android/context_selection_client.h

+// Copyright 2017 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.
+
+#ifndef CONTENT_BROWSER_ANDROID_CONTEXT_SELECTION_CLIENT_H_
+#define CONTENT_BROWSER_ANDROID_CONTEXT_SELECTION_CLIENT_H_
+
+#include <jni.h>
+
+#include "base/android/jni_weak_ref.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "content/public/browser/web_contents.h"

[Ted C, 2017/03/29 17:43:50]

do we need this since we are forward declaring it below?

[Tima Vaisburd, 2017/03/29 22:56:36]

Removed and replaced with the proper headers.

+
+namespace content {
+
+class WebContents;
+
+class ContextSelectionClient {

[Ted C, 2017/03/29 17:43:50]

Can we add a class level document that describes why and when this should be
used?

[Tima Vaisburd, 2017/03/29 22:56:36]

Absolutely! Added comments to this file, is this the class level document that
you meant?

+ public:
+  ContextSelectionClient(JNIEnv* env,
+                         const base::android::JavaRef<jobject>& obj,
+                         WebContents* web_contents);
+  ~ContextSelectionClient();

[Ted C, 2017/03/29 17:43:50]

should we mark this with override?

or can this be private since it should only be deleted by the user data?

[Tima Vaisburd, 2017/03/29 22:56:37]

I made it private. For this I had to declare the nested class UserData as the
friend of this class and to supply the UserData's unique_ptr with a custom
deleter. Another option would be to say
  friend std::unique_ptr<ContextSelectionClient>::deleter_type;
(both ideas are from
http://stackoverflow.com/questions/15193108/c-unique-ptr-versus-friend-class-...).

I'm not sure whether it worth the trouble though.

+
+  void RequestSurroundingText(JNIEnv* env,
+                              const base::android::JavaParamRef<jobject>& obj,
+                              int callback_data);
+  void CancelAllRequests(JNIEnv* env,
+                         const base::android::JavaParamRef<jobject>& obj);
+
+ private:
+  class UserData;

[Ted C, 2017/03/29 17:43:50]

why is this in the header?

[Tima Vaisburd, 2017/03/29 22:56:37]

Compiler did not understand the nested class UserData without this for me.

+
+  void OnSurroundingTextReceived(int callback_data,
+                                 const base::string16& text,
+                                 int start,
+                                 int end);
+
+  // A weak reference to the Java ContentSelectionClient object.
+  JavaObjectWeakGlobalRef java_ref_;
+
+  // WebContents is used to find the relevant RenderFrameHost that can send
+  // the request for the text.
+  WebContents* web_contents_;
+
+  base::WeakPtrFactory<ContextSelectionClient> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContextSelectionClient);
+};
+
+bool RegisterContextSelectionClient(JNIEnv* env);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_CONTEXT_SELECTION_CLIENT_H_