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}
void RenderWidgetHostImpl::SetPageFocus(bool focused) {
  is_focused_ = focused;

  if (!focused) {
    if (IsMouseLocked())
      view_->UnlockMouse();

    if (IsKeyboardLocked())
      UnlockKeyboard();

    if (auto* touch_emulator = GetExistingTouchEmulator())
      touch_emulator->CancelTouch();
  } else if (keyboard_lock_allowed_) {
    LockKeyboard();
  }

  GetWidgetInputHandler()->SetFocus(focused);

  if (RenderViewHost::From(this) && delegate_)
    delegate_->ReplicatePageFocus(focused);
}

void RenderWidgetHostImpl::SetPageFocus(bool focused) {
  is_focused_ = focused;

  if (!focused) {
    if (IsMouseLocked())
      view_->UnlockMouse();

    if (IsKeyboardLocked())
      UnlockKeyboard();

    if (auto* touch_emulator = GetExistingTouchEmulator())
      touch_emulator->CancelTouch();
  } else if (keyboard_lock_allowed_) {
    LockKeyboard();
  }

  GetWidgetInputHandler()->SetFocus(focused);

  if (RenderViewHost::From(this) && delegate_)
    delegate_->ReplicatePageFocus(focused);
}
