Fix mac pumps potentially doing nothing in DoRun()

Prior to this patch, DoRun() in MessagePumpNSRunLoop and
MessagePumpNSApplication didn't handle well the case where keep_running_
is initially false.

This situation reproduces in the convoluted scenario of deferred quits
that involve yet another nested loop being started exactly between the
quit request and its deferred execution, which is actually exercised in
some browser tests.

The proposed solution mimics what other analogous pumps do.

Bug: 787551
Change-Id: Ida8c93f9bc189477e5ad16f86e88ac1613160ba2
Reviewed-on: https://chromium-review.googlesource.com/782563Reviewed-by: Mike Pinkerton <pinkerton@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521709}

base/message_loop/message_pump_mac.mm

@@ -8,6 +8,7 @@
 
 #include <limits>
 
+#include "base/auto_reset.h"
 #include "base/logging.h"
 #include "base/mac/call_with_eh_frame.h"
 #include "base/mac/scoped_cftyperef.h"
@@ -719,13 +720,13 @@ MessagePumpNSRunLoop::~MessagePumpNSRunLoop() {
 }
 
 void MessagePumpNSRunLoop::DoRun(Delegate* delegate) {
+  AutoReset<bool> auto_reset_keep_running(&keep_running_, true);
+
   while (keep_running_) {
     // NSRunLoop manages autorelease pools itself.
     [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode
                              beforeDate:[NSDate distantFuture]];
   }
-
-  keep_running_ = true;
 }
 
 void MessagePumpNSRunLoop::Quit() {
@@ -789,6 +790,7 @@ MessagePumpNSApplication::~MessagePumpNSApplication() {
 }
 
 void MessagePumpNSApplication::DoRun(Delegate* delegate) {
+  AutoReset<bool> auto_reset_keep_running(&keep_running_, true);
   bool last_running_own_loop_ = running_own_loop_;
 
   // NSApp must be initialized by calling:
@@ -815,7 +817,6 @@ void MessagePumpNSApplication::DoRun(Delegate* delegate) {
         [NSApp sendEvent:event];
       }
     }
-    keep_running_ = true;
   }
 
   running_own_loop_ = last_running_own_loop_;

ui/base/cocoa/constrained_window/constrained_window_animation_unittest.mm

@@ -7,7 +7,6 @@
 #include <memory>
 
 #include "base/mac/scoped_nsobject.h"
-#include "base/message_loop/message_pump_mac.h"
 #import "ui/gfx/test/ui_cocoa_test_helper.h"
 
 // This class runs an animation for exactly two frames then end it.
@@ -15,7 +14,6 @@
     : NSObject<NSAnimationDelegate> {
  @private
   CGFloat frameCount_;
-  std::unique_ptr<base::MessagePumpNSRunLoop> message_pump_;
 }
 
 - (void)runAnimation:(NSAnimation*)animation;
@@ -24,12 +22,6 @@
 
 @implementation ConstrainedWindowAnimationTestDelegate
 
-- (id)init {
-  if ((self = [super init]))
-    message_pump_.reset(new base::MessagePumpNSRunLoop);
-  return self;
-}
-
 - (float)animation:(NSAnimation*)animation
     valueForProgress:(NSAnimationProgress)progress {
   ++frameCount_;
@@ -40,7 +32,6 @@
 
 - (void)animationDidEnd:(NSAnimation*)animation {
   EXPECT_EQ(2, frameCount_);
-  message_pump_->Quit();
 }
 
 - (void)runAnimation:(NSAnimation*)animation {
@@ -49,7 +40,7 @@
   [animation setDuration:600];
   [animation setDelegate:self];
   [animation startAnimation];
-  message_pump_->Run(NULL);
+  EXPECT_EQ(2, frameCount_);
 }
 
 @end
@@ -57,7 +48,7 @@
 class ConstrainedWindowAnimationTest : public ui::CocoaTest {
  protected:
   ConstrainedWindowAnimationTest() : CocoaTest() {
-    delegate_.reset([[ConstrainedWindowAnimationTestDelegate alloc] init]);
+    delegate_.reset([ConstrainedWindowAnimationTestDelegate alloc]);
   }
 
   base::scoped_nsobject<ConstrainedWindowAnimationTestDelegate> delegate_;