Exclude unused strings and files from iOS build

Change-Id: Icdc8ce22ae2ae017a11e8ccf2de64feedac456b7
Bug: 1014711
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1953231Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Mustafa Emre Acer <meacer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#722513}

components/security_interstitials/core/BUILD.gn

@@ -34,6 +34,8 @@ static_library("core") {
 
   if (is_ios) {
     sources -= [
+      "blocked_interception_ui.cc",
+      "blocked_interception_ui.h",
       "mitm_software_ui.cc",
       "mitm_software_ui.h",
     ]

components/security_interstitials_strings.grdp

@@ -64,10 +64,6 @@
     Applications that can cause this error include antivirus, firewall, and web-filtering or proxy software.
   </message>
 
-  <message name="IDS_BLOCKED_INTERCEPTION_HEADING" desc="Large heading of the known interception interstitial.">
-    Your activity on <ph name="HOSTNAME">$1<ex>example.com</ex></ph> is being monitored
-  </message>
-
   <!-- Lookalike URL warning -->
   <message name="IDS_LOOKALIKE_URL_TITLE" desc="Tab title. Context: the requested URL might be trying to trick the user since it looks like a more popular URL. This interstitial points the user to the safe site instead.">
     Safety warning
@@ -469,6 +465,12 @@
     <ph name='LOOKALIKE_DOMAIN'>$1<ex>fake-google.com</ex></ph> looks similar to <ph name='SUGGESTED_DOMAIN'>$2<ex>google.com</ex></ph>. Attackers sometimes mimic sites by using similar URLs.
   </message>
 
+  <if expr="not is_ios">
+    <!-- Blocked interception interstitial strings -->
+    <message name="IDS_BLOCKED_INTERCEPTION_HEADING" desc="Large heading of the known interception interstitial.">
+      Your activity on <ph name="HOSTNAME">$1<ex>example.com</ex></ph> is being monitored
+    </message>
+
     <!-- Known interception disclosure WebUI strings -->
     <!-- Title of the tab -->
     <message name="IDS_KNOWN_INTERCEPTION_TITLE" desc="Title of network interception disclosure page.">
@@ -502,4 +504,5 @@
     <message name="IDS_KNOWN_INTERCEPTION_INFOBAR_BUTTON_TEXT" desc="Text of the button to close the disclosure infobar and continue using Chrome.">
       OK
     </message>
+  </if>
 </grit-part>