Using WebContents::UpdateTitleForEntry() instead of NavigationEntry::SetTitle()

NavigationEntry::SetTitle() doesn't result in the emission of
WebContentsObserver::TitleWasSet() events. This used to cause listeners like
the task manager to show wrong titles of tabs (for example in the event of an
interstitial page).

BUG=607074
TEST=content_browsertests --gtest_filter=InterstitialPageImplTest.*
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2086423005
Cr-Commit-Position: refs/heads/master@{#405485}

• chrome/browser/devtools/devtools_ui_bindings.cc[diff]
• chrome/browser/media/tab_desktop_media_list_unittest.cc[diff]
• chrome/browser/task_management/providers/web_contents/web_contents_task_provider.cc[diff]
• chrome/browser/ui/browser_commands.cc[diff]
• chrome/browser/ui/search/search_tab_helper.cc[diff]
• chrome/browser/ui/toolbar/back_forward_menu_model_unittest.cc[diff]
• chrome/test/base/browser_with_test_window_test.cc[diff]
• content/browser/frame_host/interstitial_page_impl.cc[diff]
• content/browser/frame_host/interstitial_page_impl_browsertest.cc[diff]
• content/browser/frame_host/navigation_controller_impl_unittest.cc[diff]
• content/browser/web_contents/web_contents_impl.cc[diff]
• content/browser/web_contents/web_contents_impl.h[diff]
• content/public/browser/navigation_entry.h[diff]
• content/public/browser/web_contents.h[diff]
• extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc[diff]