Change Chrome behavior on handling Android executables on CrOS.

ARC++ allows Android app to run on Chrome OS. It is necessary to change
the behavior of Chrome on CrOS on handling apk and dex files. This CL
prevents auto download apk and dex file on CrOS and also disallow auto
open such files.

BUG=694872

CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2778283003
Cr-Commit-Position: refs/heads/master@{#460583}

chrome/browser/resources/safe_browsing/download_file_types.asciipb

@@ -8,7 +8,7 @@
 ##
 ## Top level settings
 ##
-version_id: 8
+version_id: 9
 sampled_ping_probability: 0.01
 default_file_type {
   uma_value: 18
@@ -2649,6 +2649,11 @@ file_types {
     danger_level: ALLOW_ON_USER_GESTURE
     auto_open_hint: DISALLOW_AUTO_OPEN
   }
+  platform_settings {
+    platform: PLATFORM_CHROME_OS
+    danger_level: ALLOW_ON_USER_GESTURE
+    auto_open_hint: DISALLOW_AUTO_OPEN
+  }
 }
 file_types {
   extension: "apk"
@@ -2659,6 +2664,11 @@ file_types {
     danger_level: ALLOW_ON_USER_GESTURE
     auto_open_hint: DISALLOW_AUTO_OPEN
   }
+  platform_settings {
+    platform: PLATFORM_CHROME_OS
+    danger_level: ALLOW_ON_USER_GESTURE
+    auto_open_hint: DISALLOW_AUTO_OPEN
+  }
   platform_settings {
     platform: PLATFORM_LINUX
     danger_level: ALLOW_ON_USER_GESTURE

chrome/common/safe_browsing/file_type_policies_unittest.cc

@@ -107,14 +107,14 @@ TEST_F(FileTypePoliciesTest, UnpackResourceBundle) {
             file_type.platform_settings(0).auto_open_hint());
 #endif
 
-  // Lookup .dex that varies on OS_ANDROID
+  // Lookup .dex that varies on OS_ANDROID and OS_CHROMEOS
   base::FilePath dex_file(FILE_PATH_LITERAL("foo.dex"));
   file_type = policies_.PolicyForFile(dex_file);
   EXPECT_EQ("dex", file_type.extension());
   EXPECT_EQ(143, file_type.uma_value());
   EXPECT_FALSE(file_type.is_archive());
   EXPECT_EQ(DownloadFileType::FULL_PING, file_type.ping_setting());
-#if defined(OS_ANDROID)
+#if defined(OS_ANDROID) || defined(OS_CHROMEOS)
   EXPECT_EQ(DownloadFileType::ALLOW_ON_USER_GESTURE,
             file_type.platform_settings(0).danger_level());
   EXPECT_EQ(DownloadFileType::DISALLOW_AUTO_OPEN,