Bug 1106593: Proguard third-party libraries that ship with Fennec. r=nalexander

This applies Proguard to third-party libraries such as the Android
support-v4 library and the Google Play Services libraries.
Previously, these were not Proguarded, bloating the Fennec APK.

Technically, this required a few work-arounds, including:

* stripping library debug information with a early Proguard
  invocation;
* altering the optimizations tried; and
* reducing the number of Proguard passes.

--HG--
rename : mobile/android/config/proguard.cfg => mobile/android/config/proguard/proguard.cfg
extra : rebase_source : 6d638695b6c8f759578aba5f1eda668fc9c28e9d
extra : amend_source : 96a475c0739c4b44a3df3fdfd2c59321836d9694

mobile/android/base/Makefile.in

@@ -60,14 +60,20 @@ GARBAGE += \
 
 GARBAGE_DIRS += classes db jars res sync services generated
 
-JAVA_BOOTCLASSPATH = \
+# The bootclasspath is functionally identical to the classpath, but allows the
+# classes given to redefine classes in core packages, such as java.lang.
+# android.jar is here as it provides Android's definition of the Java Standard
+# Library. The compatability lib here tweaks a few of the core classes to paint
+# over changes in behaviour between versions.
+JAVA_BOOTCLASSPATH := \
     $(ANDROID_SDK)/android.jar \
     $(ANDROID_COMPAT_LIB) \
     $(NULL)
 
 JAVA_BOOTCLASSPATH := $(subst $(NULL) ,:,$(strip $(JAVA_BOOTCLASSPATH)))
 
-# If native devices are enabled, add Google Play Services and some of the v7 compat libraries
+# If native devices are enabled, add Google Play Services and some of the v7
+# compat libraries.
 ifdef MOZ_NATIVE_DEVICES
     JAVA_CLASSPATH += \
         $(GOOGLE_PLAY_SERVICES_LIB) \
@@ -78,6 +84,24 @@ endif
 
 JAVA_CLASSPATH := $(subst $(NULL) ,:,$(strip $(JAVA_CLASSPATH)))
 
+# Library jars that we're bundling: these are subject to Proguard before inclusion
+# into classes.dex.
+java_bundled_libs := \
+    $(ANDROID_COMPAT_LIB) \
+    $(NULL)
+
+ifdef MOZ_NATIVE_DEVICES
+    java_bundled_libs += \
+        $(GOOGLE_PLAY_SERVICES_LIB) \
+        $(ANDROID_MEDIAROUTER_LIB) \
+        $(ANDROID_APPCOMPAT_LIB) \
+        $(NULL)
+endif
+
+java_bundled_libs := $(subst $(NULL) ,:,$(strip $(java_bundled_libs)))
+
+# All the jars we're compiling from source. (not to be confused with
+# java_bundled_libs, which holds the jars which we're including as binaries).
 ALL_JARS = \
   constants.jar \
   gecko-R.jar \
@@ -102,24 +126,20 @@ ALL_JARS += ../stumbler/stumbler.jar
 generated/org/mozilla/mozstumbler/R.java: .aapt.deps ;
 endif
 
+# The list of jars in Java classpath notation (colon-separated).
+all_jars_classpath := $(subst $(NULL) ,:,$(strip $(ALL_JARS)))
+
 include $(topsrcdir)/config/config.mk
 
-# Note that we're going to set up a dependency directly between embed_android.dex and the java files
-# Instead of on the .class files, since more than one .class file might be produced per .java file
-# Sync dependencies are provided in a single jar. Sync classes themselves are delivered as source,
-# because Android resource classes must be compiled together in order to avoid overlapping resource
-# indices.
-
-library_jars = \
-    $(JAVA_CLASSPATH) \
-    $(JAVA_BOOTCLASSPATH) \
+library_jars := \
+    $(ANDROID_SDK)/android.jar \
     $(NULL)
 
 library_jars := $(subst $(NULL) ,:,$(strip $(library_jars)))
 
 classes.dex: .proguard.deps
 	$(REPORT_BUILD)
-	$(DX) --dex --output=classes.dex jars-proguarded $(subst :, ,$(ANDROID_COMPAT_LIB):$(JAVA_CLASSPATH))
+	$(DX) --dex --output=classes.dex jars-proguarded
 
 ifdef MOZ_DISABLE_PROGUARD
   PROGUARD_PASSES=0
@@ -135,6 +155,8 @@ else
   endif
 endif
 
+proguard_config_dir=$(topsrcdir)/mobile/android/config/proguard
+
 # This stanza ensures that the set of GeckoView classes does not depend on too
 # much of Fennec, where "too much" is defined as the set of potentially
 # non-GeckoView classes that GeckoView already depended on at a certain point in
@@ -148,19 +170,41 @@ classycle_jar := $(topsrcdir)/mobile/android/build/classycle/classycle-1.4.1.jar
 		$(ALL_JARS)
 	@$(TOUCH) $@
 
-# We touch the target file before invoking Proguard so that Proguard's
-# outputs are fresher than the target, preventing a subsequent
-# invocation from thinking Proguard's outputs are stale.  This is safe
-# because Make removes the target file if any recipe command fails.
-.proguard.deps: .geckoview.deps $(ALL_JARS) $(topsrcdir)/mobile/android/config/proguard.cfg
+# First, we delete debugging information from libraries. Having line-number
+# information for libraries for which we lack the source isn't useful, so this
+# saves us a bit of space. Importantly, Proguard has a bug causing it to
+# sometimes corrupt this information if present (which it does for some of the
+# included libraries). This corruption prevents dex from completing, so we need
+# to get rid of it.  This prevents us from seeing line numbers in stack traces
+# for stack frames inside libraries.
+#
+# This step can occur much earlier than the main Proguard pass: it needs only
+# gecko-R.jar to have been compiled (as that's where the library R.java files
+# end up), but it does block the main Proguard pass.
+.bundled.proguard.deps: gecko-R.jar $(proguard_config_dir)/strip-libs.cfg
 	$(REPORT_BUILD)
 	@$(TOUCH) $@
 	java \
 		-Xmx512m -Xms128m \
 		-jar $(ANDROID_SDK_ROOT)/tools/proguard/lib/proguard.jar \
-		@$(topsrcdir)/mobile/android/config/proguard.cfg \
+		@$(proguard_config_dir)/strip-libs.cfg \
+		-injars $(subst ::,:,$(java_bundled_libs))\
+		-outjars bundled-jars-nodebug \
+		-libraryjars $(library_jars):gecko-R.jar
+
+# We touch the target file before invoking Proguard so that Proguard's
+# outputs are fresher than the target, preventing a subsequent
+# invocation from thinking Proguard's outputs are stale.  This is safe
+# because Make removes the target file if any recipe command fails.
+.proguard.deps: .geckoview.deps .bundled.proguard.deps $(ALL_JARS) $(proguard_config_dir)/proguard.cfg
+	$(REPORT_BUILD)
+	@$(TOUCH) $@
+	java \
+		-Xmx512m -Xms128m \
+		-jar $(ANDROID_SDK_ROOT)/tools/proguard/lib/proguard.jar \
+		@$(proguard_config_dir)/proguard.cfg \
 		-optimizationpasses $(PROGUARD_PASSES) \
-		-injars $(subst ::,:,$(subst $(NULL) ,:,$(strip $(ALL_JARS)))) \
+		-injars $(subst ::,:,$(all_jars_classpath)):bundled-jars-nodebug \
 		-outjars jars-proguarded \
 		-libraryjars $(library_jars)
 

mobile/android/config/proguard/play-services-keeps.cfg

@@ -0,0 +1,19 @@
+# Rules to prevent Google Play Services from exploding
+# (From http://developer.android.com/google/play-services/setup.html#Proguard
+# With the reference to "Object" changed so it'll actually *work*...)
+-keep class * extends java.util.ListResourceBundle {
+    protected java.lang.Object[][] getContents();
+}
+
+-keep public class com.google.android.gms.common.internal.safeparcel.SafeParcelable {
+    public static final *** NULL;
+}
+
+-keepnames @com.google.android.gms.common.annotation.KeepName class *
+-keepclassmembernames class * {
+    @com.google.android.gms.common.annotation.KeepName *;
+}
+
+-keepnames class * implements android.os.Parcelable {
+    public static final ** CREATOR;
+}

mobile/android/config/proguard/proguard.cfg

@@ -110,6 +110,11 @@
 -optimizations !class/merging/horizontal
 -optimizations !class/merging/vertical
 
+# This optimisation causes corrupt bytecode if we run more than two passes.
+# Testing shows that running the extra passes of everything else saves us
+# more than this optimisation does, so bye bye!
+-optimizations !code/allocation/variable
+
 # Keep miscellaneous targets.
 
 # Keep the annotation.
@@ -207,3 +212,9 @@
 
 # Suppress warnings about missing descriptor classes.
 #-dontnote **,!ch.boye.**,!org.mozilla.gecko.sync.**
+
+-include "play-services-keeps.cfg"
+
+# Don't print spurious warnings from the support library.
+# See: http://stackoverflow.com/questions/22441366/note-android-support-v4-text-icucompatics-cant-find-dynamically-referenced-cl
+-dontnote android.support.**

mobile/android/config/proguard/strip-libs.cfg

@@ -0,0 +1,40 @@
+# Proguard step for stripping debug information.
+#
+# This is useful to work around a bug in the way Proguard handles debug information: it
+# sometimes corrupts it. Classes with corrupt debug information cannot be dexed, but
+# classes with *no* debug information can be. There's no way to configure Proguard to
+# delete debug information on a per-class basis, so we need this special extra step for
+# stripping debug information only from those classes for which the Proguard bug is
+# encountered.
+#
+# Currently, this pass is applied to all bundled library jars for which we are not
+# compiling the source. This is slightly more than is strictly necessary to work around
+# the Proguard bug, but such debug information is of negligible value and stripping it
+# too slightly simplifies the makefile and saves us a handful of kilobytes of binary size.
+#
+# Configuring Proguard to do nothing except strip metadata is done by having it run only
+# the obfuscation pass, but with a configuration that prevents it from renaming any classes.
+# It then attempts to delete class metadata, so we further configure it not to do so for
+# anything except the problematic debug information.
+
+# Run only the obfuscator.
+-dontoptimize
+-dontshrink
+-dontpreverify
+-verbose
+
+# Don't rename anything.
+-keeppackagenames
+
+# Seriously, don't rename anything.
+-keep class *
+-keepclassmembers class * {
+    *;
+}
+
+# Don't delete other useful metadata.
+-keepattributes Exceptions,InnerClasses,Signature,Deprecated,*Annotation*,EnclosingMethod
+
+# Don't print spurious warnings from the support library.
+# See: http://stackoverflow.com/questions/22441366/note-android-support-v4-text-icucompatics-cant-find-dynamically-referenced-cl
+-dontnote android.support.**