Fix a DCHECK fired when switching between screen capturing and windown capturing.

content/browser/media/capture/desktop_capture_device.cc

 // Copyright (c) 2013 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 "content/browser/media/capture/desktop_capture_device.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 202 matching lines @@
     LOG(ERROR) << log;
     client_->OnError(log);
     return;
   }
 
   if (!client_)
     return;
 
   base::TimeDelta capture_time(
       base::TimeDelta::FromMilliseconds(frame->capture_time_ms()));
-  UMA_HISTOGRAM_TIMES(
-      capturer_type_ == DesktopMediaID::TYPE_SCREEN ? kUmaScreenCaptureTime
-                                                    : kUmaWindowCaptureTime,
-      capture_time);
+
+  // The two UMA_ blocks must be put in its own scope since it creates a static
+  // variable which expected constant histogram name.
+  if (capturer_type_ == DesktopMediaID::TYPE_SCREEN) {
+    UMA_HISTOGRAM_TIMES(kUmaScreenCaptureTime, capture_time);
+  } else {
+    UMA_HISTOGRAM_TIMES(kUmaWindowCaptureTime, capture_time);
+  }
 
   scoped_ptr<webrtc::DesktopFrame> owned_frame(frame);
 
   // On OSX We receive a 1x1 frame when the shared window is minimized. It
   // cannot be subsampled to I420 and will be dropped downstream. So we replace
   // it with a black frame to avoid the video appearing frozen at the last
   // frame.
   if (frame->size().width() == 1 || frame->size().height() == 1) {
     if (!black_frame_.get()) {
       black_frame_.reset(
@@ skipping 236 matching lines @@
 #else
   base::MessageLoop::Type thread_type = base::MessageLoop::TYPE_DEFAULT;
 #endif
 
   thread_.StartWithOptions(base::Thread::Options(thread_type, 0));
 
   core_.reset(new Core(thread_.message_loop_proxy(), capturer.Pass(), type));
 }
 
 }  // namespace content