Making sure we don't take a GestureNav screenshot unless the history position changes.

Only take a screenshot if the page id changes.

Looking at NavigationControllerImpl::ClassifyNavigation(), I think this is the
right check. If we could move the code for taking the screenshot post
controller_->RendererDidNavigate() call, we'd be able to use the NavigationType
calculated in that method, but based on the comments for the screenshot code,
this doesn't seem like a safe thing to do.


BUG=375921

Review URL: https://codereview.chromium.org/316553007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@275324 0039d316-1c4b-4281-b951-d872f2087c98

content/browser/frame_host/navigator_impl.cc

@@ -426,8 +426,25 @@ void NavigatorImpl::DidNavigate(
       // calling RenderFrameHostManager::DidNavigateMainFrame, because that can
       // change WebContents::GetRenderViewHost to return the new host, instead
       // of the one that may have just been swapped out.
-      if (delegate_->CanOverscrollContent())
-        controller_->TakeScreenshot();
+      if (delegate_->CanOverscrollContent()) {
+        bool page_id_changed;
+        bool url_changed;
+        NavigationEntry* current_entry = controller_->GetLastCommittedEntry();
+        if (current_entry) {
+          page_id_changed = params.page_id > 0 &&
+              params.page_id != current_entry->GetPageID();
+          url_changed = params.url != current_entry->GetURL();
+        } else {
+          page_id_changed = params.page_id > 0;
+          url_changed = params.url != GURL::EmptyGURL();
+        }
+
+        // We only want to take the screenshot if the are navigating to a
+        // different history entry than the current one. So if neither the
+        // page id nor the url changed - don't take the screenshot.
+        if (page_id_changed || url_changed)
+          controller_->TakeScreenshot();
+      }
 
       // Run tasks that must execute just before the commit.
       delegate_->DidNavigateMainFramePreCommit(params);