Moving flags out of base_proguard_config make it usable by other .apks

chrome/android/java/proguard.flags

Index: chrome/android/java/proguard.flags
diff --git a/chrome/android/java/proguard.flags b/chrome/android/java/proguard.flags
index cf546d1ba7ebc350d2eac18eebae58716d6d46b8..66c91494e963ea605f086f0478eedeb9d08d8bec 100644
--- a/chrome/android/java/proguard.flags
+++ b/chrome/android/java/proguard.flags
@@ -3,6 +3,25 @@
   *;
 }
 
+# The following chart was created on July 20, 2016, to decide on 3 optimization
+# passes.
+# optimization passes | time | .dex size | dirty memory per process
+# -----------------------------------------------------------------
+#          1          | 0:48 |  5805676  |         488972
+#          2          | 1:07 |  5777376  |         487092
+#          3          | 1:24 |  5772192  |         486596
+#          4          | 1:42 |  5771124  |         486484
+#          5          | 1:56 |  5770504  |         486432
+-optimizationpasses 3
+
+# Class merging messes up stacktraces beyond the point of them being
+# deobfuscatable. If turned on, it would give us a 2% reduction in .dex size.
+-optimizations !class/merging/*
+
+# Allowing Proguard to change modifiers. This change shrinks the .dex size by
+# ~1.1%, and reduces the method count by ~4.3%.
+-allowaccessmodification
+
 # Fragments are loaded using reflection via Fragment.instantiate(Context,String)
 # This can be improved upon - see crbug.com/622023.
 -keep public class com.google.android.apps.chrome** extends android.app.Fragment