Merge: Fix the filtering logic for x-chrome-manage-account header

Merge: Fix the filtering logic for x-chrome-manage-account header

The current code checks if the request is loaded in a main frame and if it
is triggered by a user gesture. As per discussion with eisinger@ there is
no reliable way to associate a request with a user gesture, instead
we should check if the requested resource type is a main frame resource.

BUG=394869
TBR=guohui@chromium.org

Review URL: https://codereview.chromium.org/632803002

Cr-Commit-Position: refs/heads/master@{#298372}
(cherry picked from commit 564d209d5733494ca2847eef75161151e1dd0f24)

Committed: https://chromium.googlesource.com/chromium/src/+/994f60059a7280d84e672a350f7525af0956c15e

[guohui, 2014-10-10 17:41:47]

Committed patchset #1 (id:1) manually as
994f60059a7280d84e672a350f7525af0956c15e (presubmit successful).