Refactoring the weak_ptr_factory order content/browser folder

Changing in the intialization order of WeakPtrFactory such that all
member variables should appear before the WeakPtrFactory to ensure
that any WeakPtrs to Controller are invalidated before its members
variable's destructors are executed, rendering them invalid.

BUG=303818

Review URL: https://codereview.chromium.org/567943002

Cr-Commit-Position: refs/heads/master@{#295238}
10 files changed