WebAPKs: Fix play-install variations check

WebAPKs: Fix play-install variations check

This CL:
1) Fixes ChromeWebApkHost#canUseGooglePlayToInstallWebApk() to use
variations::GetVariationParamValueByFeature() instead of
variations::GetVariationParamValue(). This matches the server side variations
configuration.
2) Updates the cached value of whether WebAPKs are enabled (Returned by
ChromeWebApkHost#isEnabled()) prior to calling
ChromeWebApkHost#canUseGooglePlayToInstallWebApk().

BUG=684804
Review-Url: https://codereview.chromium.org/2655803002
Cr-Commit-Position: refs/heads/master@{#446097}
(cherry picked from commit 2a1ffdc2376233aaef5110a1c406a50539a795bd)

Review-Url: https://codereview.chromium.org/2654093006 .
Cr-Commit-Position: refs/branch-heads/2987@{#129}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/c99788f98ca6aba368c4dc1431ddae2a9ccdbb26

[pkotwicz, 2017-01-26 23:34:46]

Description was changed from

==========
WebAPKs: Fix play-install variations check

This CL:
1) Fixes ChromeWebApkHost#canUseGooglePlayToInstallWebApk() to use
variations::GetVariationParamValueByFeature() instead of
variations::GetVariationParamValue(). This matches the server side variations
configuration.
2) Updates the cached value of whether WebAPKs are enabled (Returned by
ChromeWebApkHost#isEnabled()) prior to calling
ChromeWebApkHost#canUseGooglePlayToInstallWebApk().

BUG=684804

Review-Url: https://codereview.chromium.org/2655803002
Cr-Commit-Position: refs/heads/master@{#446097}
(cherry picked from commit 2a1ffdc2376233aaef5110a1c406a50539a795bd)
==========

to

==========
WebAPKs: Fix play-install variations check

This CL:
1) Fixes ChromeWebApkHost#canUseGooglePlayToInstallWebApk() to use
variations::GetVariationParamValueByFeature() instead of
variations::GetVariationParamValue(). This matches the server side variations
configuration.
2) Updates the cached value of whether WebAPKs are enabled (Returned by
ChromeWebApkHost#isEnabled()) prior to calling
ChromeWebApkHost#canUseGooglePlayToInstallWebApk().

BUG=684804

Review-Url: https://codereview.chromium.org/2655803002
Cr-Commit-Position: refs/heads/master@{#446097}
(cherry picked from commit 2a1ffdc2376233aaef5110a1c406a50539a795bd)

Review-Url: https://codereview.chromium.org/2654093006 .
Cr-Commit-Position: refs/branch-heads/2987@{#129}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/c99788f98ca6aba368c4dc1431dd...
==========

[pkotwicz, 2017-01-26 23:34:47]

Committed patchset #1 (id:1) manually as
c99788f98ca6aba368c4dc1431ddae2a9ccdbb26.