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This CL adds a static FrameTree::GloballyFindByID that can be used by to find a FrameTreeNode given a frame tree node id.

BUG=376082

Review URL: https://codereview.chromium.org/429603002

Cr-Commit-Position: refs/heads/master@{#289513}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289513 0039d316-1c4b-4281-b951-d872f2087c98