overscroll: Take a screenshot at more appropriate times.

content/browser/web_contents/navigation_controller_impl.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/browser/web_contents/navigation_controller_impl.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/logging.h"
@@ skipping 475 matching lines @@
   NavigationEntryImpl* entry =
       NavigationEntryImpl::FromNavigationEntry(GetLastCommittedEntry());
   if (!entry)
     return;
 
   RenderViewHost* render_view_host = web_contents_->GetRenderViewHost();
   content::RenderWidgetHostView* view = render_view_host->GetView();
   if (!view)
     return;
 
+  if (!take_screenshot_callback_.is_null())
+    take_screenshot_callback_.Run(render_view_host);
+
   skia::PlatformBitmap* temp_bitmap = new skia::PlatformBitmap;
   render_view_host->CopyFromBackingStore(gfx::Rect(),
       view->GetViewBounds().size(),
       base::Bind(&NavigationControllerImpl::OnScreenshotTaken,
                  base::Unretained(this),
                  entry->GetUniqueID(),
                  base::Owned(temp_bitmap)),
       temp_bitmap);
 }
 
@@ skipping 240 matching lines @@
   LoadEntry(entry);
 }
 
 void NavigationControllerImpl::DocumentLoadedInFrame() {
   is_initial_navigation_ = false;
 }
 
 bool NavigationControllerImpl::RendererDidNavigate(
     const ViewHostMsg_FrameNavigate_Params& params,
     LoadCommittedDetails* details) {
-  // When navigating away from the current page, take a screenshot of it in the
-  // current state so that it can be used during an overscroll-navigation
-  // gesture.
-  if (details->is_main_frame)
-    TakeScreenshot();
-
   // Save the previous state before we clobber it.
   if (GetLastCommittedEntry()) {
     details->previous_url = GetLastCommittedEntry()->GetURL();
     details->previous_entry_index = GetLastCommittedEntryIndex();
   } else {
     details->previous_url = GURL();
     details->previous_entry_index = -1;
   }
 
   // If we have a pending entry at this point, it should have a SiteInstance.
@@ skipping 904 matching lines @@
                           new NavigationEntryImpl(*source.entries_[i])));
     }
   }
 }
 
 void NavigationControllerImpl::SetGetTimestampCallbackForTest(
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
+void NavigationControllerImpl::SetTakeScreenshotCallbackForTest(
+    const base::Callback<void(RenderViewHost*)>& take_screenshot_callback) {
+  take_screenshot_callback_ = take_screenshot_callback;
+}
+
 }  // namespace content