Turning on optimizations for chromium code

This saves us 357kb of .dex size and 44kb of memory per process.

BUG=625704

Review-Url: https://codereview.chromium.org/2127973003
Cr-Commit-Position: refs/heads/master@{#406099}

build/android/gyp/proguard.py

@@ -12,6 +12,15 @@ from util import build_utils
 from util import proguard_util
 
 
+_DANGEROUS_OPTIMIZATIONS = [
+    # See crbug.com/625992
+    "code/allocation/variable",
+    # See crbug.com/625994
+    "field/propagation/value",
+    "method/propagation/parameter",
+    "method/propagation/returnvalue",
+]
+
 def _ParseOptions(args):
   parser = optparse.OptionParser()
   build_utils.AddDepfileOption(parser)
@@ -31,6 +40,8 @@ def _ParseOptions(args):
   parser.add_option('--classpath', action='append',
                     help='Classpath for proguard.')
   parser.add_option('--stamp', help='Path to touch on success.')
+  parser.add_option('--enable-dangerous-optimizations', action='store_true',
+                    help='Enable optimizations which are known to have issues.')
   parser.add_option('--verbose', '-v', action='store_true',
                     help='Print all proguard output')
 
@@ -62,6 +73,8 @@ def main(args):
   classpath = list(set(options.classpath))
   proguard.libraryjars(classpath)
   proguard.verbose(options.verbose)
+  if not options.enable_dangerous_optimizations:
+    proguard.disable_optimizations(_DANGEROUS_OPTIMIZATIONS)
 
   input_paths = proguard.GetInputs()
 

build/android/gyp/util/proguard_util.py

@@ -45,6 +45,7 @@ class ProguardCmdBuilder(object):
     self._outjar = None
     self._cmd = None
     self._verbose = False
+    self._disabled_optimizations = []
 
   def outjar(self, path):
     assert self._cmd is None
@@ -87,6 +88,10 @@ class ProguardCmdBuilder(object):
     assert self._cmd is None
     self._verbose = verbose
 
+  def disable_optimizations(self, optimizations):
+    assert self._cmd is None
+    self._disabled_optimizations += optimizations
+
   def build(self):
     if self._cmd:
       return self._cmd
@@ -123,6 +128,9 @@ class ProguardCmdBuilder(object):
         '-libraryjars', ':'.join(self._libraries),
       ]
 
+    for optimization in self._disabled_optimizations:
+      cmd += [ '-optimizations', '!' + optimization ]
+
     cmd += [
       '-injars', ':'.join(self._injars)
     ]

build/config/android/internal_rules.gni

@@ -701,6 +701,11 @@ if (enable_java_templates) {
       if (defined(invoker.args)) {
         args += invoker.args
       }
+      if (defined(invoker.proguard_jar_path)) {
+        # We assume that if we are using a different ProGuard, this new version
+        # can handle the 'dangerous' optimizaions.
+        args += [ "--enable-dangerous-optimizations" ]
+      }
     }
   }
 

chrome/android/java/proguard.flags

@@ -5,7 +5,7 @@
 -keep @interface ***
 
 # Disable obfuscation for the following two packages.
--keepnames class com.google.android.apps.chrome.**,org.chromium.** {
+-keepnames,allowoptimization class com.google.android.apps.chrome.**,org.chromium.** {
   *;
 }