Increase DevTools' GPU info watchdog to 20s on Linux Debug.

These bots are crashing with the 5s timeout.

BUG=796437
TBR=zmo@chromium.org, pfeldman@chromium.org

Change-Id: I2c2b9b491af93a7dcce86a27f6d5af68bb2ee81f
Reviewed-on: https://chromium-review.googlesource.com/835475Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#525249}

content/browser/devtools/protocol/system_info_handler.cc

@@ -12,6 +12,7 @@
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "build/build_config.h"
 #include "content/browser/gpu/compositor_util.h"
 #include "content/browser/gpu/gpu_data_manager_impl.h"
 #include "gpu/config/gpu_feature_type.h"
@@ -31,7 +32,12 @@ using SystemInfo::GPUInfo;
 using GetInfoCallback = SystemInfo::Backend::GetInfoCallback;
 
 // Give the GPU process a few seconds to provide GPU info.
+// Linux Debug builds need more time -- see Issue 796437.
+#if defined(OS_LINUX) && !defined(NDEBUG)
+const int kGPUInfoWatchdogTimeoutMs = 20000;
+#else
 const int kGPUInfoWatchdogTimeoutMs = 5000;
+#endif
 
 class AuxGPUInfoEnumerator : public gpu::GPUInfo::Enumerator {
  public: