PM: Only enable instrumentation under the chrome embedder.

As of, content/
no longer provides forwarding for the ResourceCoordinator
instrumentation interfaces. This was a step in a larger refactoring,
but had the effect of orphaning the instrumentation in all but the
chrome/browser embedder. This in turn led to a memory regression in
the Android WebView.
This CL makes the initialization and the usage of the instrumentation
interfaces conditional on a runtime flag, which is only set by the
This is still an intermediate state in the refactoring, as the
interfaces in question will be moved and simplified.

Bug: 926426
Change-Id: Ia640f544b536bf86d53e853de6178aeaf9c9b6f5
Commit-Queue: Sigurður Ásgeirsson <>
Reviewed-by: Daniel Cheng <>
Reviewed-by: Stephen White <>
Reviewed-by: Chris Hamilton <>
Cr-Commit-Position: refs/heads/master@{#638575}
14 files changed