Add UMA for testing whether device supports memory mapping APK files with executable permissions.

base/android/library_loader/library_loader_hooks.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/android/library_loader/library_loader_hooks.h"
 
 #include "base/android/command_line_android.h"
 #include "base/android/jni_string.h"
 #include "base/at_exit.h"
 #include "base/metrics/histogram.h"
@@ skipping 28 matching lines @@
 
   // Low-memory browser loads at fixed address, success or fail.
   LOW_MEMORY_LFA_SUCCESS = 1,
   LOW_MEMORY_LFA_BACKOFF_USED = 2,
 
   MAX_BROWSER_HISTOGRAM_CODE = 3,
 };
 
 RendererHistogramCode g_renderer_histogram_code = NO_PENDING_HISTOGRAM_CODE;
 
+enum LibraryLoadFromApkSupportCode {
+  // The device's support for loading a library directly from the APK file.
+  NOT_SUPPORTED = 0,
+  SUPPORTED = 1,
+
+  MAX_LIBRARY_LOAD_FROM_APK_SUPPORT_CODE = 2,
+};
+
 } // namespace
 
 static void RegisterChromiumAndroidLinkerRendererHistogram(
     JNIEnv* env,
     jclass clazz,
     jboolean requested_shared_relro,
     jboolean load_at_fixed_address_failed) {
   // Note a pending histogram value for later recording.
   if (requested_shared_relro) {
     g_renderer_histogram_code = load_at_fixed_address_failed
@@ skipping 10 matching lines @@
   UMA_HISTOGRAM_ENUMERATION("ChromiumAndroidLinker.RendererStates",
                             g_renderer_histogram_code,
                             MAX_RENDERER_HISTOGRAM_CODE);
   g_renderer_histogram_code = NO_PENDING_HISTOGRAM_CODE;
 }
 
 static void RecordChromiumAndroidLinkerBrowserHistogram(
     JNIEnv* env,
     jclass clazz,
     jboolean is_using_browser_shared_relros,
-    jboolean load_at_fixed_address_failed) {
+    jboolean load_at_fixed_address_failed,
+    jboolean library_load_from_apk_supported) {
   // For low-memory devices, record whether or not we successfully loaded the
   // browser at a fixed address. Otherwise just record a normal invocation.
   BrowserHistogramCode histogram_code;
   if (is_using_browser_shared_relros) {
     histogram_code = load_at_fixed_address_failed
                      ? LOW_MEMORY_LFA_BACKOFF_USED : LOW_MEMORY_LFA_SUCCESS;
   } else {
     histogram_code = NORMAL_LRA_SUCCESS;
   }
   UMA_HISTOGRAM_ENUMERATION("ChromiumAndroidLinker.BrowserStates",
                             histogram_code,
                             MAX_BROWSER_HISTOGRAM_CODE);
+

[rmcilroy, 2014/10/13 11:08:19]

nit - remove newline

[petrcermak, 2014/10/13 12:12:46]

I would prefer to keep it there to make it clear that the two histograms are
independent. Instead, I added a comment describing the new UMA call.

+  UMA_HISTOGRAM_ENUMERATION("ChromiumAndroidLinker.LibraryLoadFromApkSupported",
+                            library_load_from_apk_supported ?
+                                SUPPORTED : NOT_SUPPORTED,
+                            MAX_LIBRARY_LOAD_FROM_APK_SUPPORT_CODE);
 }
 
 void SetLibraryLoadedHook(LibraryLoadedHook* func) {
   g_registration_callback = func;
 }
 
 static void InitCommandLine(JNIEnv* env, jclass clazz,
                             jobjectArray init_command_line) {
   InitNativeCommandLineFromJavaArray(env, init_command_line);
 }
@@ skipping 26 matching lines @@
 jstring GetVersionNumber(JNIEnv* env, jclass clazz) {
   return ConvertUTF8ToJavaString(env, g_library_version_number).Release();
 }
 
 static void RecordNativeLibraryHack(JNIEnv*, jclass, jboolean usedHack) {
   UMA_HISTOGRAM_BOOLEAN("LibraryLoader.NativeLibraryHack", usedHack);
 }
 
 }  // namespace android
 }  // namespace base