Modify iOSShell-gyp to generate unique bundle identifier

BUG=skia:

Review URL: https://codereview.chromium.org/1483143002
diff --git a/experimental/iOSShell/iOSShell-Info.plist b/experimental/iOSShell/iOSShell-Info.plist
index 69b62ef..7f1a827 100644
--- a/experimental/iOSShell/iOSShell-Info.plist
+++ b/experimental/iOSShell/iOSShell-Info.plist
@@ -11,7 +11,7 @@
 	<key>CFBundleIconFile</key>
 	<string></string>
 	<key>CFBundleIdentifier</key>
-	<string>com.google.iOSShell</string>
+	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundleName</key>
diff --git a/gyp/iOSShell.gyp b/gyp/iOSShell.gyp
index 3f3acdc..2ec50db 100644
--- a/gyp/iOSShell.gyp
+++ b/gyp/iOSShell.gyp
@@ -68,6 +68,7 @@
             '../src/views/mac',
           ],
           'xcode_settings' : {
+            'PRODUCT_BUNDLE_IDENTIFIER' : '<!(echo com.google.iOSShell.`hostname | md5`)',
             'INFOPLIST_FILE' : '../experimental/iOSShell/iOSShell-Info.plist',
           },
           'xcode_config_file': '../experimental/iOSSampleApp/SkiOSSampleApp-Base.xcconfig',
diff --git a/platform_tools/ios/bin/ios_setup.sh b/platform_tools/ios/bin/ios_setup.sh
index 53a33c6..dbfed7c 100755
--- a/platform_tools/ios/bin/ios_setup.sh
+++ b/platform_tools/ios/bin/ios_setup.sh
@@ -18,9 +18,6 @@
 # Temporary location to assemble the app into an .ipa package.
 IOS_PCKG_DIR="/tmp/ios_pckg"
 
-# Bundle id of the app that runs the tests.
-TEST_RUNNER_BUNDLE_ID="com.google.iOSShell"
-
 # Directory with the Skia source.
 SKIA_SRC_DIR=$(cd "${SCRIPT_DIR}/../../.."; pwd)
 
@@ -30,7 +27,7 @@
 # Code Signing identity - this needs to be set up on the local machine.
 CODE_SIGN_IDENTITY="iPhone Developer"
 
-IOS_BUNDLE_ID="com.google.iOSShell"
+IOS_BUNDLE_ID="com.google.iOSShell.`hostname | md5`"
 
 IOS_RESULTS_DIR="results"
 
@@ -94,7 +91,7 @@
   if [[ ! -d "$IOS_MOUNT_POINT" ]]; then
     mkdir -p $IOS_MOUNT_POINT
   fi
-  ifuse --container $TEST_RUNNER_BUNDLE_ID $IOS_MOUNT_POINT
+  ifuse --container $IOS_BUNDLE_ID $IOS_MOUNT_POINT
   sleep 1
   >&2 echo "Successfully mounted device."
 }