Flash: Use better APIs for preventing sleep

The API that this was using on Mac has been deprecated, and is
preventing us from upgrading our SDK version. We have a cross-platform
sleep-preventation API. Use that instead.

The Flash API for preventing power is a bit idiosyncratic in that it
doesn't create and destroy power blockers, but rather says "please don't
go to sleep for a while", where "a while" is not defined. Empirically,
twitch.tv called this method every 10 seconds. Use a timeout of 45
seconds to be safe.

BUG=650797

Review-Url: https://codereview.chromium.org/2388313004
Cr-Commit-Position: refs/heads/master@{#425843}
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index 99a41ebc..d00f3bfe 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -1419,6 +1419,7 @@
     "//crypto:platform",
     "//device/base",
     "//device/bluetooth:mojo",
+    "//device/power_save_blocker",
     "//device/usb/mojo",
     "//device/usb/public/interfaces",
     "//google_apis",