Move OverscrollController to RenderWidgetHostViewAura

content/browser/frame_host/navigation_entry_screenshot_manager.cc

 // 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.
 
 #include "content/browser/frame_host/navigation_entry_screenshot_manager.h"
 
 #include "base/command_line.h"
 #include "base/threading/worker_pool.h"
 #include "content/browser/frame_host/navigation_controller_impl.h"
 #include "content/browser/frame_host/navigation_entry_impl.h"
@@ skipping 80 matching lines @@
   if (!overscroll_enabled)
     return;
 
   NavigationEntryImpl* entry =
       NavigationEntryImpl::FromNavigationEntry(owner_->GetLastCommittedEntry());
   if (!entry)
     return;
 
   RenderViewHost* render_view_host =
       owner_->delegate()->GetRenderViewHost();
-  if (!static_cast<RenderViewHostImpl*>
+  // TODO(jdduke): Determine if necessary?
+  /*if (!static_cast<RenderViewHostImpl*>
       (render_view_host)->overscroll_controller()) {
     return;
-  }
+  }*/

[sadrul, 2014/05/22 16:18:27]

The screenshots are used only when overscroll is turned on at the moment. This
is to avoid having to take the screenshots if they are not going to be used.

[jdduke (slow), 2014/05/22 16:21:31]

Any ideas on another way to plumb through this data? I'd hate to do some ugly
casting if this can be used on platforms besides Aura (I believe we compile it
for all platforms?).

[sadrul, 2014/05/22 16:53:20]

We compile it on all platforms, yeah.

Maybe we could have a static bool OverscrollController::IsEnabled() that looks
at the cmd-line flag?

[jdduke (slow), 2014/05/22 19:29:38]

Hmm, I started down that road and found some runtime cases where it starts to
get messy.  I added a |CanOverscrollContent()| to the nav delegate that I think
gets us most of the way there (and the method is actually already implemented
generically in the WebContentsImpl).

   content::RenderWidgetHostView* view = render_view_host->GetView();
   if (!view)
     return;
 
   // Make sure screenshots aren't taken too frequently.
   base::Time now = base::Time::Now();
   if (now - last_screenshot_time_ <
           base::TimeDelta::FromMilliseconds(min_screenshot_interval_ms_)) {
     return;
   }
@@ skipping 172 matching lines @@
         owner_->GetEntryAtIndex(forward));
     if (ClearScreenshot(entry))
       --screenshot_count;
     ++forward;
   }
   CHECK_GE(screenshot_count, 0);
   CHECK_LE(screenshot_count, kMaxScreenshots);
 }
 
 }  // namespace content