First step in enabling creating tabs without an Activity on Android.

content/public/browser/content_browser_client.cc

 // Copyright (c) 2012 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 "content/public/browser/content_browser_client.h"
 
 #include "base/files/file_path.h"
 #include "ui/gfx/image/image_skia.h"
 #include "url/gurl.h"
 
@@ skipping 324 matching lines @@
     MediaStreamType type) {
   return false;
 }
 
 PresentationServiceDelegate*
 ContentBrowserClient::GetPresentationServiceDelegate(
     WebContents* web_contents) {
   return nullptr;
 }
 
-WebContents* ContentBrowserClient::OpenURL(BrowserContext* browser_context,
-                                           const OpenURLParams& params) {
-  return nullptr;

[mlamouri (slow - plz ping), 2015/02/09 12:07:37]

May I suggest to keep a default implementation and do something like:
  callback->Run(nullptr);

It would be unfortunate to have someone not implementing that method and then
have a pending callback.

[Peter Beverloo, 2015/02/10 17:49:37]

I'd prefer not to, as that breaks the API contract that the callback will be
invoked when the WC* is available. If someone uses OpenURL() on a platform where
it's not supported then they'll get the NOTIMPLEMENTED() message in either case.

[mlamouri (slow - plz ping), 2015/02/11 13:50:23]

How would they get NOTIMPLEMENTED()? That's in the chrome/ layer, right? If
someone, let say Opera is implementing a ContentBrowserClient, this call would
silently fail.

Maybe you could just have a NOTIMPLEMENTED() in there?

[Peter Beverloo, 2015/02/11 16:18:27]

Right. That's true. I've added the "callback.Run(nullptr);" you initially
suggested since that's what the rest of the ContentBrowserClient default
implementations do. The DCHECK will lead them up the stack to the new method.

-}
-
 #if defined(OS_WIN)
 const wchar_t* ContentBrowserClient::GetResourceDllName() {
   return nullptr;
 }
 #endif
 
 #if defined(VIDEO_HOLE)
 ExternalVideoSurfaceContainer*
 ContentBrowserClient::OverrideCreateExternalVideoSurfaceContainer(
     WebContents* web_contents) {
   return nullptr;
 }
 #endif
 
 }  // namespace content