Fix MediaSession gradle file to use modulePrefix

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=162610352

extensions/mediasession/build.gradle

@@ -25,7 +25,7 @@ android {
 }
 }
 
 
 dependencies {
 dependencies {
-    compile project(':library-core')
+    compile project(modulePrefix + 'library-core')
     compile 'com.android.support:support-media-compat:' + supportLibraryVersion
     compile 'com.android.support:support-media-compat:' + supportLibraryVersion
     compile 'com.android.support:appcompat-v7:' + supportLibraryVersion
     compile 'com.android.support:appcompat-v7:' + supportLibraryVersion
 }
 }