Fix WeakPtrFactory member ordering in content
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
Committed:
https://crrev.com/61b4d4b053ec88e368a55ebc27f3219027aac6e1
Cr-Commit-Position: refs/heads/master@{#296656}