Start rendering timer after first navigation

Currently the new content rendering timer in the browser process,
which clears an old page's contents 4 seconds after a navigation if the
new page doesn't draw in that time, is not set on the first navigation
for a top-level frame.

This is problematic because content can exist before the first
navigation, for instance if it was created by a javascript: URL.

This CL removes the code that skips the timer activation on the first
navigation.

Bug: 844881
Change-Id: I19b3ad1ff62c69ded3a5f7b1c0afde191aaf4584
Reviewed-on: https://chromium-review.googlesource.com/1188589
Reviewed-by: Fady Samuel <fsamuel@chromium.org>
Reviewed-by: ccameron <ccameron@chromium.org>
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#586913}
TouchEmulator* RenderWidgetHostImpl::GetExistingTouchEmulator() {
  if (!delegate_ || !delegate_->GetInputEventRouter() ||
      !delegate_->GetInputEventRouter()->has_touch_emulator()) {
    return nullptr;
  }

  return delegate_->GetInputEventRouter()->GetTouchEmulator();
}

TouchEmulator* RenderWidgetHostImpl::GetExistingTouchEmulator() {
  if (!delegate_ || !delegate_->GetInputEventRouter() ||
      !delegate_->GetInputEventRouter()->has_touch_emulator()) {
    return nullptr;
  }

  return delegate_->GetInputEventRouter()->GetTouchEmulator();
}
