arc: Stop waiting for crash reporter on UI thread

components/arc/crash_collector/arc_crash_collector_bridge.cc

 // Copyright 2016 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 "components/arc/crash_collector/arc_crash_collector_bridge.h"
 
 #include <sysexits.h>
 #include <unistd.h>
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/process/launch.h"
 #include "mojo/edk/embedder/embedder.h"
 
 namespace {
+
 const char kCrashReporterPath[] = "/sbin/crash_reporter";
+
+// Waits for the process to exit.
+void WaitForProcessToExit(base::Process process) {
+  int exit_code = 0;
+  if (!process.WaitForExit(&exit_code)) {
+    LOG(ERROR) << "Failed to wait for " << kCrashReporterPath;
+  } else if (exit_code != EX_OK) {
+    LOG(ERROR) << kCrashReporterPath << " failed with exit code " << exit_code;
+  }
+}
+
 }
 
 namespace arc {
 
-ArcCrashCollectorBridge::ArcCrashCollectorBridge(ArcBridgeService* bridge)
-    : ArcService(bridge), binding_(this) {
+ArcCrashCollectorBridge::ArcCrashCollectorBridge(
+    ArcBridgeService* bridge,
+    scoped_refptr<base::TaskRunner> blocking_task_runner)
+    : ArcService(bridge),
+      blocking_task_runner_(blocking_task_runner),
+      binding_(this) {
   arc_bridge_service()->crash_collector()->AddObserver(this);
 }
 
 ArcCrashCollectorBridge::~ArcCrashCollectorBridge() {
   arc_bridge_service()->crash_collector()->RemoveObserver(this);
 }
 
 void ArcCrashCollectorBridge::OnInstanceReady() {
   mojom::CrashCollectorHostPtr host_ptr;
   binding_.Bind(mojo::GetProxy(&host_ptr));
@@ skipping 10 matching lines @@
       std::make_pair(handle.get().handle, STDIN_FILENO)};
 
   base::LaunchOptions options;
   options.fds_to_remap = &fd_map;
 
   auto process =
       base::LaunchProcess({kCrashReporterPath, "--arc_java_crash=" + type.get(),
                            "--arc_device=" + device_, "--arc_board=" + board_,
                            "--arc_cpu_abi=" + cpu_abi_},
                           options);
-
-  int exit_code;
-  if (!process.WaitForExit(&exit_code)) {
-    LOG(ERROR) << "Failed to wait for " << kCrashReporterPath;
-  } else if (exit_code != EX_OK) {
-    LOG(ERROR) << kCrashReporterPath << " failed with exit code " << exit_code;
-  }
+  blocking_task_runner_->PostTask(FROM_HERE,

[hidehiko, 2016/09/26 14:17:22]

Optional: How about moving everything, incl. LaunchProcess, to blocking task
runner? It looks ok to do, according to the client side code.

[hashimoto, 2016/09/27 06:48:26]

Done.

+                                  base::Bind(&WaitForProcessToExit,
+                                             base::Passed(std::move(process))));
 }
 
 void ArcCrashCollectorBridge::SetBuildProperties(const mojo::String& device,
                                                  const mojo::String& board,
                                                  const mojo::String& cpu_abi) {
   device_ = device.get();
   board_ = board.get();
   cpu_abi_ = cpu_abi.get();
 }
 
 }  // namespace arc