base::CopyFile can copy *from* Android's content scheme.

base/files/file_util_posix.cc

Index: base/files/file_util_posix.cc
diff --git a/base/files/file_util_posix.cc b/base/files/file_util_posix.cc
index b8c0eeb94c0088d07aa41f7e4e7bf593ea72094d..0e9fbb94a409dc86c39004bb79d65f80a4063af5 100644
--- a/base/files/file_util_posix.cc
+++ b/base/files/file_util_posix.cc
@@ -880,22 +880,29 @@ bool MoveUnsafe(const FilePath& from_path, const FilePath& to_path) {
 // Mac has its own implementation, this is for all other Posix systems.
 bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
   ThreadRestrictions::AssertIOAllowed();
-  int infile = HANDLE_EINTR(open(from_path.value().c_str(), O_RDONLY));
-  if (infile < 0)
+  File infile;
+#if defined(OS_ANDROID)
+  if (from_path.IsContentUri()) {
+    infile = OpenContentUriForRead(from_path);
+  } else {
+    infile = File(from_path, File::FLAG_OPEN | File::FLAG_READ);
+  }
+#else
+  infile = File(from_path, File::FLAG_OPEN | File::FLAG_READ);
+#endif
+  if (!infile.IsValid())
     return false;
 
-  int outfile = HANDLE_EINTR(creat(to_path.value().c_str(), 0666));
-  if (outfile < 0) {
-    close(infile);
+  File outfile(to_path, File::FLAG_WRITE | File::FLAG_CREATE_ALWAYS);
+  if (!outfile.IsValid())
     return false;
-  }
 
   const size_t kBufferSize = 32768;
   std::vector<char> buffer(kBufferSize);
   bool result = true;
 
   while (result) {
-    ssize_t bytes_read = HANDLE_EINTR(read(infile, &buffer[0], buffer.size()));
+    ssize_t bytes_read = infile.ReadAtCurrentPos(&buffer[0], buffer.size());
     if (bytes_read < 0) {
       result = false;
       break;
@@ -905,10 +912,8 @@ bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
     // Allow for partial writes
     ssize_t bytes_written_per_read = 0;
     do {
-      ssize_t bytes_written_partial = HANDLE_EINTR(write(
-          outfile,
-          &buffer[bytes_written_per_read],
-          bytes_read - bytes_written_per_read));
+      ssize_t bytes_written_partial = outfile.WriteAtCurrentPos(
+          &buffer[bytes_written_per_read], bytes_read - bytes_written_per_read);
       if (bytes_written_partial < 0) {
         result = false;
         break;
@@ -917,11 +922,6 @@ bool CopyFileUnsafe(const FilePath& from_path, const FilePath& to_path) {
     } while (bytes_written_per_read < bytes_read);
   }
 
-  if (IGNORE_EINTR(close(infile)) < 0)
-    result = false;
-  if (IGNORE_EINTR(close(outfile)) < 0)
-    result = false;
-
   return result;
 }
 #endif  // !defined(OS_MACOSX)