Desktop chrome tab capture-chooseDesktopMedia()

content/public/browser/desktop_media_id.h

 // Copyright 2013 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_PUBLIC_BROWSER_DESKTOP_MEDIA_ID_H_
 #define CONTENT_PUBLIC_BROWSER_DESKTOP_MEDIA_ID_H_
 
 #include <string>
 #include <tuple>
 
 #include "content/common/content_export.h"
+#include "content/public/browser/web_contents_media_capture_id.h"
 
 #if defined(USE_AURA)
 namespace aura {
 class Window;
 }  // namespace aura
 #endif  // defined(USE_AURA)
 
 namespace content {
 
 // Type used to identify desktop media sources. It's converted to string and
 // stored in MediaStreamRequest::requested_video_device_id.
 struct CONTENT_EXPORT DesktopMediaID {
  public:
-  enum Type {
-    TYPE_NONE,
-    TYPE_SCREEN,
-    TYPE_WINDOW,
-  };
+  enum Type { TYPE_NONE, TYPE_SCREEN, TYPE_WINDOW, TYPE_TAB };

[Avi (use Gerrit), 2016/01/08 17:11:39]

Whoa, whoa. Now we're getting into sketchy territory.

Content knows about screens and windows. Once you get into having tabs, that's a
ui decision that belongs to the embedder, and I'm not comfortable having that
knowledge leak into Content.

I'm not seeing the full picture here, but I'm a bit weirded out.

[GeorgeZ, 2016/01/08 19:39:02]

This class actually is a part of the implementation to support JaveScript
chrome.desktopCapture https://developer.chrome.com/extensions/desktopCapture. in
the document, DesktopCaptureSourceType enums "screen", "window", or "tab".
Sharing a tab should hide private information such as bookmarks if a browser
window is shared instead.

If this didn't address your question, please clarify it.

[miu, 2016/01/08 19:49:56]

Avi makes a good point here, and I should have caught this myself in a prior
round of this code review (sorry).  What he means is that libcontent has no
knowledge of tabs.  Tabs is a UI concept in the Chrome browser, but other
embedders of libcontent (such as content_shell) don't use the "tabs" concept. 
Therefore, any libcontent code should instead be referring to a WebContents (a
WebContents instance is 1:1 with a tab in the Chrome browser).

So, maybe TYPE_WEB_CONTENT or TYPE_PAGE would be more appropriate here?  Also,
consider updating your design so that the "tab" DesktopCaptureSourceType enum is
something like "content" or "page" instead.

 
   typedef intptr_t Id;
 
   // Represents an "unset" value for either |id| or |aura_id|.
   static const Id kNullId = 0;
 
 #if defined(USE_AURA)
   // Assigns integer identifier to the |window| and returns its DesktopMediaID.
   static DesktopMediaID RegisterAuraWindow(Type type, aura::Window* window);
 
   // Returns the Window that was previously registered using
   // RegisterAuraWindow(), else nullptr.
   static aura::Window* GetAuraWindowById(const DesktopMediaID& id);
 #endif  // defined(USE_AURA)
 
-  static DesktopMediaID Parse(const std::string& str);
-
   DesktopMediaID() = default;
 
-  DesktopMediaID(Type type, Id id)
-      : type(type),
-        id(id) {
-  }
+  DesktopMediaID(Type type, Id id) : type(type), id(id) {}
+
+  DesktopMediaID(Type type, Id id, WebContentsMediaCaptureId tab_id)
+      : type(type), id(id), tab_id(tab_id) {}
 
   // Operators so that DesktopMediaID can be used with STL containers.
-  bool operator<(const DesktopMediaID& other) const {
-#if defined(USE_AURA)
-    return std::tie(type, id, aura_id) <
-           std::tie(other.type, other.id, other.aura_id);
-#else
-    return std::tie(type, id) < std::tie(other.type, other.id);
-#endif
-  }
-  bool operator==(const DesktopMediaID& other) const {
-#if defined(USE_AURA)
-    return type == other.type && id == other.id && aura_id == other.aura_id;
-#else
-    return type == other.type && id == other.id;
-#endif
-  }
+  bool operator<(const DesktopMediaID& other) const;
+  bool operator==(const DesktopMediaID& other) const;
 
-  bool is_null() { return type == TYPE_NONE; }
-
-  std::string ToString();
+  bool is_null() const { return type == TYPE_NONE; }
+  std::string ToString() const;
+  static DesktopMediaID Parse(const std::string& str);
 
   Type type = TYPE_NONE;
 
   // The IDs referring to the target native screen or window.  |id| will be
   // non-null if and only if it refers to a native screen/window.  |aura_id|
   // will be non-null if and only if it refers to an Aura window.  Note that is
   // it possible for both of these to be non-null, which means both IDs are
   // referring to the same logical window.
   Id id = kNullId;
 #if defined(USE_AURA)
   // TODO(miu): Make this an int, after clean-up for http://crbug.com/513490.
   Id aura_id = kNullId;
 #endif
+
+  // This id contains information for tab capture.
+  WebContentsMediaCaptureId tab_id;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_DESKTOP_MEDIA_ID_H_