Ensure that android "release" apps are signed with debug key

Review URL: https://codereview.chromium.org/1275223003
diff --git a/platform_tools/android/apps/sample_app/build.gradle b/platform_tools/android/apps/sample_app/build.gradle
index e2986e0..def446a 100644
--- a/platform_tools/android/apps/sample_app/build.gradle
+++ b/platform_tools/android/apps/sample_app/build.gradle
@@ -10,6 +10,7 @@
         targetSdkVersion 19
         versionCode 1
         versionName "1.0"
+        signingConfig signingConfigs.debug
     }
 
     sourceSets.main.jni.srcDirs = [] //disable automatic ndk-build call
diff --git a/platform_tools/android/bin/android_install_app b/platform_tools/android/bin/android_install_app
index 83b879f..01a792e 100755
--- a/platform_tools/android/bin/android_install_app
+++ b/platform_tools/android/bin/android_install_app
@@ -56,7 +56,7 @@
 
 if [[ "$BUILDTYPE" == "Release" ]];
 then
-    apk_suffix="release-unsigned.apk"
+    apk_suffix="release.apk"
 else
     apk_suffix="debug.apk"
 fi
diff --git a/platform_tools/android/gyp/skia_android.gypi b/platform_tools/android/gyp/skia_android.gypi
index 4e32fcb..47dbf7a 100644
--- a/platform_tools/android/gyp/skia_android.gypi
+++ b/platform_tools/android/gyp/skia_android.gypi
@@ -39,7 +39,7 @@
         'android_variant%': "mips64",
       }],
       [ 'android_buildtype == "Release"', {
-        'android_apk_suffix': "release-unsigned.apk",
+        'android_apk_suffix': "release.apk",
       }, {
         'android_apk_suffix': "debug.apk",
       }],