Bug Fix: Title Case for Picker Window Title

On Mac, desktop capture picker window's title is using sentence case, but by convention, it should be in title case.

This CL Fixes the bug.

BUG=644905

Review-Url: https://codereview.chromium.org/2319303002
Cr-Commit-Position: refs/heads/master@{#417422}

chrome/app/generated_resources.grd

@@ -13878,9 +13878,16 @@ Please check your email at <ph name="ACCOUNT_EMAIL">$2<ex>jane.doe@gmail.com</ex
       </message>
 
       <!-- Desktop media picker UI for Desktop Capture API -->
-      <message name="IDS_DESKTOP_MEDIA_PICKER_TITLE" desc="Title for the window picker dialog shown when desktop capture is requested by an app.">
-        Share your screen
-      </message>
+      <if expr="not use_titlecase">
+        <message name="IDS_DESKTOP_MEDIA_PICKER_TITLE" desc="Title for the window picker dialog shown when desktop capture is requested by an app.">
+          Share your screen
+        </message>
+      </if>
+      <if expr="use_titlecase">
+        <message name="IDS_DESKTOP_MEDIA_PICKER_TITLE" desc="Title for the window picker dialog shown when desktop capture is requested by an app.">
+          Share Your Screen
+        </message>
+      </if>
       <message name="IDS_DESKTOP_MEDIA_PICKER_TITLE_DEPRECATED" desc="Title for the window picker dialog shown when desktop capture is requested by an app.">
         Share your screen - <ph name="APP_NAME">$1<ex>Google Hangouts</ex></ph>
       </message>