Fix a regression in chrome://gpucrash etc.

So we won't have a GpuUIHost with id 0.  It starts from 1.

BUG=105044
TEST=GPUCrashTest.Kill on GPU bots
Review URL: http://codereview.chromium.org/8680035

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@111721 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 16 insertions, 3 deletions

diff --git a/chrome/browser/browser_about_handler.cc b/chrome/browser/browser_about_handler.cc
index 3998524..1d3eb95 100644
--- a/chrome/browser/browser_about_handler.cc
+++ b/chrome/browser/browser_about_handler.cc
@@ -1562,15 +1562,15 @@ bool WillHandleBrowserAboutURL(GURL* url,
     // Induce an intentional crash in the browser process.
     CHECK(false);
   } else if (host == chrome::kChromeUIGpuCleanHost) {
-    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::FromID(0);
+    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::GetOneInstance();
     if (shim)
       shim->SimulateRemoveAllContext();
   } else if (host == chrome::kChromeUIGpuCrashHost) {
-    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::FromID(0);
+    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::GetOneInstance();
     if (shim)
       shim->SimulateCrash();
   } else if (host == chrome::kChromeUIGpuHangHost) {
-    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::FromID(0);
+    GpuProcessHostUIShim* shim = GpuProcessHostUIShim::GetOneInstance();
     if (shim)
       shim->SimulateHang();
 #if defined(OS_CHROMEOS)
diff --git a/content/browser/gpu/gpu_process_host_ui_shim.cc b/content/browser/gpu/gpu_process_host_ui_shim.cc
index e7bda6d..5c992e2 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.cc
+++ b/content/browser/gpu/gpu_process_host_ui_shim.cc
@@ -131,6 +131,15 @@ GpuProcessHostUIShim* GpuProcessHostUIShim::FromID(int host_id) {
   return g_hosts_by_id.Pointer()->Lookup(host_id);
 }
 
+// static
+GpuProcessHostUIShim* GpuProcessHostUIShim::GetOneInstance() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  if (g_hosts_by_id.Pointer()->IsEmpty())
+    return NULL;
+  IDMap<GpuProcessHostUIShim>::iterator it(g_hosts_by_id.Pointer());
+  return it.GetCurrentValue();
+}
+
 bool GpuProcessHostUIShim::Send(IPC::Message* msg) {
   DCHECK(CalledOnValidThread());
   return BrowserThread::PostTask(BrowserThread::IO,
diff --git a/content/browser/gpu/gpu_process_host_ui_shim.h b/content/browser/gpu/gpu_process_host_ui_shim.h
index b274bad..976a559 100644
--- a/content/browser/gpu/gpu_process_host_ui_shim.h
+++ b/content/browser/gpu/gpu_process_host_ui_shim.h
@@ -66,6 +66,10 @@ class GpuProcessHostUIShim
 
   CONTENT_EXPORT static GpuProcessHostUIShim* FromID(int host_id);
 
+  // Get a GpuProcessHostUIShim instance; it doesn't matter which one.
+  // Return NULL if none has been created.
+  CONTENT_EXPORT static GpuProcessHostUIShim* GetOneInstance();
+
   // IPC::Channel::Sender implementation.
   virtual bool Send(IPC::Message* msg) OVERRIDE;