[CrOS] Update strings used on cellular status change

Protocol Configuration Options, or PCOs, are information elements
contained in certain cellular messages. While PCOs can serve many
purposes, a notable use is in informing the user equipment (UE) of
the state of the network it is connected to. Changes such as activating
a network or running out of data, for example, result in a change of
a field within received PCOs.

The text to be displayed to the user on PCO status change no longer
matches the strings in chromeos_strings.grdp. This CL updates those
strings correspondingly.

Bug: 888118
Change-Id: I0cf94ed4151baec9cc43b84cbf41ecf5bd5a9f7f
Reviewed-on: https://chromium-review.googlesource.com/1238478
Commit-Queue: Alex Khouderchah <akhouderchah@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593761}

chrome/app/chromeos_strings.grdp

@@ -1182,10 +1182,10 @@
     Connection to <ph name="name">$1<ex>Google VPN</ex></ph> has been lost
   </message>
   <message name="IDS_NETWORK_OUT_OF_CREDITS_TITLE" desc="Title for network out of data error notification">
-    Network connection error
+    Couldn't connect
   </message>
   <message name="IDS_NETWORK_OUT_OF_CREDITS_BODY" desc="Message body for network out of data error notification">
-    You may have used up your mobile data allowance. Visit the <ph name="name">$1<ex>GoogleGuest</ex></ph> activation portal to buy more data.
+    You may have used up your mobile data allowance. Visit the <ph name="name">$1<ex>GoogleGuest</ex></ph> activation portal to buy more data
   </message>
   <message name="IDS_NETWORK_UNRECOGNIZED_ERROR" desc="Unrecognized Network error text">
     Unrecognized error: <ph name="desc">$1<ex>ShillErrorString</ex></ph>
@@ -1194,13 +1194,13 @@
     Mobile data activated
   </message>
   <message name="IDS_NETWORK_CELLULAR_ACTIVATED" desc="Text of the cellular activated notification">
-    Congratulations! Your '<ph name="name">$1<ex>Generic Wireless</ex></ph>' data service has been activated and is ready to go.
+    Your '<ph name="name">$1<ex>Generic Wireless</ex></ph>' data service is ready to use
   </message>
   <message name="IDS_NETWORK_ACTIVATION_ERROR_TITLE" desc="Title for network activation error notification">
-    Network activation error
+    Couldn't connect
   </message>
   <message name="IDS_NETWORK_ACTIVATION_NEEDS_CONNECTION" desc="Message when attempting to activate a mobile network that requires a connection">
-    Activation of '<ph name="name">$1<ex>Generic Wireless</ex></ph>' requires a network connection.
+    To activate '<ph name="name">$1<ex>Generic Wireless</ex></ph>' data, first connect to a Wi-Fi network
   </message>
 
   <!-- Strings shown within Tether notifications -->