[EasyUnlock] Observe proximity changes and clean up TX power strategy.

chrome/app/generated_resources.grd

Index: chrome/app/generated_resources.grd
diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index a71e2d2e608768709cfa028e3492f821a5e741c9..369ec1610be9567648ab547c4031da013a3c19e5 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -11698,12 +11698,9 @@ Please check your email at <ph name="ACCOUNT_EMAIL">$2<ex>jane.doe@gmail.com</ex
         To keep your <ph name="DEVICE_TYPE">$1<ex>Chromebook</ex></ph> safe, Smart Lock for Chromebook requires a screen lock on your phone.
       </message>
       <message name="IDS_EASY_UNLOCK_SCREENLOCK_TOOLTIP_RSSI_TOO_LOW" desc="Tooltip for an icon on a user's lock screen pod shown by Easy Unlock when a phone eligible to unlock the Chromebook is detected, but it's not in the Chromebook's proximity (> 30 feet away).">
-        Can’t find your phone. Make sure it’s within arm’s reach.
-      </message>
-      <message name="IDS_EASY_UNLOCK_SCREENLOCK_TOOLTIP_TX_POWER_TOO_HIGH" desc="Tooltip for an icon on a user's lock screen pod shown by Easy Unlock when a phone eligible to unlock the Chromebook is detected, but it's not in the Chromebook's proximity (> 1 foot away).">
         Bring your phone closer to your <ph name="DEVICE_TYPE">$1<ex>Chromebook</ex></ph> to enter.
       </message>
-      <message name="IDS_EASY_UNLOCK_SCREENLOCK_TOOLTIP_PHONE_LOCKED_AND_TX_POWER_TOO_HIGH" desc="Tooltip for an icon on a user's lock screen pod shown by Easy Unlock when a phone eligible to unlock the Chromebook is detected, but it's both (a) locked and (b) not in the Chromebook's proximity (> 1 foot away).">
+      <message name="IDS_EASY_UNLOCK_SCREENLOCK_TOOLTIP_PHONE_LOCKED_AND_RSSI_TOO_LOW" desc="Tooltip for an icon on a user's lock screen pod shown by Easy Unlock when a phone eligible to unlock the Chromebook is detected, but it's both (a) locked and (b) not in the Chromebook's proximity (> 1 foot away).">
         Unlock your phone and bring it closer to your <ph name="DEVICE_TYPE">$1<ex>Chromebook</ex></ph> to enter.
       </message>
       <message name="IDS_EASY_UNLOCK_SCREENLOCK_TOOLTIP_INITIAL_AUTHENTICATED" desc="Tooltip text shown on lock screen when a phone eligible to unlock the Chromebook via Easy Unlock is detected and authenticated for the first time.">