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

base/android/java/src/org/chromium/base/library_loader/Linker.java

Index: base/android/java/src/org/chromium/base/library_loader/Linker.java
diff --git a/base/android/java/src/org/chromium/base/library_loader/Linker.java b/base/android/java/src/org/chromium/base/library_loader/Linker.java
index 93f05de9a93692c5d2608806e939334d2568a07e..521517841ca5ca9e95144077c985f2a40b8e2abc 100644
--- a/base/android/java/src/org/chromium/base/library_loader/Linker.java
+++ b/base/android/java/src/org/chromium/base/library_loader/Linker.java
@@ -136,7 +136,7 @@ import javax.annotation.Nullable;
  *
  *    This behaviour is altered by the BROWSER_SHARED_RELRO_CONFIG configuration
  *    variable below, which may force the browser to load the libraries at
- *    fixed addresses to.
+ *    fixed addresses too.
  *
  *  - Once all libraries are loaded in the browser process, one can call
  *    getSharedRelros() which returns a Bundle instance containing a map that
@@ -382,6 +382,19 @@ public class Linker {
     }
 
     /**
+     * Call this method to determine if the linker is running in the browser
+     * process.
+     *
+     * @return true if the linker is running in the browser process.
+     */
+    public static boolean isInBrowserProcess() {
+        synchronized (Linker.class) {
+            ensureInitializedLocked();
+            return sInBrowserProcess;
+        }
+    }
+
+    /**
      * Call this method to determine if the chromium project must load
      * the library directly from the zip file.
      */
@@ -820,6 +833,25 @@ public class Linker {
     }
 
     /**
+     * Check whether the device supports memory mapping APK files with executable
+     * permissions.
+     *
+     * @param apkFile Filename of the APK.
+     * @return true if supported.
+     */
+    public static boolean checkApkMemoryMappingSupport(String apkFile) {
+        synchronized (Linker.class) {
+            ensureInitializedLocked();
+
+            if (DEBUG) Log.i(TAG, "checkApkMemoryMappingSupport: " + apkFile);
+            boolean supported = nativeCheckApkMemoryMappingSupport(apkFile);
+            if (DEBUG) Log.i(TAG, "Memory mapping APK files with executable permissions " +
+                    (supported ? "" : "NOT ") + "supported");
+            return supported;
+        }
+    }
+
+    /**
      * Move activity from the native thread to the main UI thread.
      * Called from native code on its own thread.  Posts a callback from
      * the UI thread back to native code.
@@ -917,6 +949,16 @@ public class Linker {
     private static native long nativeGetRandomBaseLoadAddress(long sizeBytes);
 
     /**
+     * Native method which checks whether the device supports memory mapping APK
+     * files with executable permissions
+     *
+     * @param apkFile Filename of the APK.
+     * @return true if supported.
+     *
+     */
+    private static native boolean nativeCheckApkMemoryMappingSupport(String apkFile);
+
+    /**
      * Record information for a given library.
      * IMPORTANT: Native code knows about this class's fields, so
      * don't change them without modifying the corresponding C++ sources.