ash: Fix a screen-locking crash.

ash/wm/lock_state_controller.cc

Index: ash/wm/lock_state_controller.cc
diff --git a/ash/wm/lock_state_controller.cc b/ash/wm/lock_state_controller.cc
index 09a46afa2a1436404485a642a920205f69a4cad8..cb2b1dc99cc02e443bd8da846f12026b1f063fac 100644
--- a/ash/wm/lock_state_controller.cc
+++ b/ash/wm/lock_state_controller.cc
@@ -16,6 +16,7 @@
 #include "ash/wm/session_state_animator.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
+#include "base/strings/string_util.h"
 #include "base/timer/timer.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/compositor/layer_animation_sequence.h"
@@ -584,34 +585,36 @@ void LockStateController::LockAnimationCancelled() {
 }
 
 void LockStateController::PreLockAnimationFinished(bool request_lock) {
-  can_cancel_lock_animation_ = false;
   VLOG(1) << "PreLockAnimationFinished";
-  if (request_lock) {
-    Shell::GetInstance()->metrics()->RecordUserMetricsAction(
-        shutdown_after_lock_ ?
-        UMA_ACCEL_LOCK_SCREEN_POWER_BUTTON :
-        UMA_ACCEL_LOCK_SCREEN_LOCK_BUTTON);
-    delegate_->RequestLockScreen();
+  can_cancel_lock_animation_ = false;
+  if (!request_lock)
+    return;
+
+  if (system_is_locked_) {

[Daniel Erat, 2014/08/01 22:55:07]

another option would be structuring the body of this method like this:

  if (request_lock)
    // request lock
  if (!system_is_locked_)
    // start timer

otherwise, we're not running the timer at all when locking using means other
than the power button. there's a bit more risk that doing that may not fix the
crashes, though (i.e. if the pre-lock animation is run sometimes without a
corresponding lock request). this class isn't well-tested, so maybe it's safest
to just stick with what i have here.

+    LOG(DFATAL) << "Got request to lock already-locked system at completion "
+                << "of pre-lock animation";
+    return;
   }
 
-  int lock_timeout = kLockFailTimeoutMs;
+  Shell::GetInstance()->metrics()->RecordUserMetricsAction(
+      shutdown_after_lock_ ?
+      UMA_ACCEL_LOCK_SCREEN_POWER_BUTTON :
+      UMA_ACCEL_LOCK_SCREEN_LOCK_BUTTON);
+  delegate_->RequestLockScreen();
 
+  base::TimeDelta timeout =
+      base::TimeDelta::FromMilliseconds(kLockFailTimeoutMs);
 #if defined(OS_CHROMEOS)
-  std::string board = base::SysInfo::GetLsbReleaseBoard();
-
   // Increase lock timeout for slower hardware, see http://crbug.com/350628
+  const std::string board = base::SysInfo::GetLsbReleaseBoard();
   if (board == "x86-mario" ||
-      board.substr(0, 8) == "x86-alex" ||
-      board.substr(0, 7) == "x86-zgb") {
-    lock_timeout *= 2;
+      StartsWithASCII(board, "x86-alex", true) ||
+      StartsWithASCII(board, "x86-zgb", true)) {
+    timeout *= 2;
   }
 #endif
-
   lock_fail_timer_.Start(
-      FROM_HERE,
-      base::TimeDelta::FromMilliseconds(lock_timeout),
-      this,
-      &LockStateController::OnLockFailTimeout);
+      FROM_HERE, timeout, this, &LockStateController::OnLockFailTimeout);
 }
 
 void LockStateController::PostLockAnimationFinished() {