Make gyp tool to emit FDO Support for android.

pylib/gyp/generator/android.py

Index: pylib/gyp/generator/android.py
diff --git a/pylib/gyp/generator/android.py b/pylib/gyp/generator/android.py
index d7aa9029deae81f1db4002ab1e3f689cccb1bcbe..34db9800f938aefd379555598d45006a861487fb 100644
--- a/pylib/gyp/generator/android.py
+++ b/pylib/gyp/generator/android.py
@@ -503,9 +503,29 @@ class AndroidMkWriter(object):
 
       self.WriteLn('\n# Flags passed to only C++ (and not C) files.')
       self.WriteList(config.get('cflags_cc'), 'LOCAL_CPPFLAGS_%s' % configname)
+      if int(config.get('android_enable_fdo', 0)):
+        use_fdo = 'true'
+      else:
+        use_fdo = 'false'
+      self.WriteLn('\nLOCAL_FDO_SUPPORT_%s := %s' % (configname, use_fdo))
 
     self.WriteLn('\nLOCAL_CFLAGS := $(MY_CFLAGS_$(GYP_CONFIGURATION)) '
                  '$(MY_DEFS_$(GYP_CONFIGURATION))')
+    self.WriteLn(
+        'LOCAL_FDO_SUPPORT := $(LOCAL_FDO_SUPPORT_$(GYP_CONFIGURATION))')
+
+    self.WriteLn('\nifneq ($(strip $(TARGET_FDO_CFLAGS)),)')
+    self.WriteLn('  ifeq ($(strip $(LOCAL_FDO_SUPPORT)), true)')
+    self.WriteLn(
+        '    LOCAL_CFLAGS := $(patsubst -Os,-O2,$(LOCAL_CFLAGS))')
+    self.WriteLn(
+        '    fdo_incompatible_flags=-fno-early-inlining -finline-limit=%')
+    self.WriteLn(
+        '    LOCAL_CFLAGS := $(filter-out $(fdo_incompatible_flags),'
+        '$(LOCAL_CFLAGS))')
+    self.WriteLn('  endif')
+    self.WriteLn('endif\n')
+
     # Undefine ANDROID for host modules
     # TODO: the source code should not use macro ANDROID to tell if it's host
     # or target module.