Resume WebKit shared timers only in previously suspended processes.

content/browser/android/content_view_statics.cc

Index: content/browser/android/content_view_statics.cc
diff --git a/content/browser/android/content_view_statics.cc b/content/browser/android/content_view_statics.cc
index 0fb08964dea3514f57c01e6fe384a81a52edd89d..66af8652d49bf14b038ce79820903053657bcfd2 100644
--- a/content/browser/android/content_view_statics.cc
+++ b/content/browser/android/content_view_statics.cc
@@ -3,25 +3,64 @@
 // found in the LICENSE file.
 
 #include <jni.h>
+#include <vector>
 
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/basictypes.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "content/browser/android/content_view_statics.h"
 #include "content/common/android/address_parser.h"
 #include "content/common/view_messages.h"
 #include "content/public/browser/render_process_host.h"
-
 #include "jni/ContentViewStatics_jni.h"
 
 using base::android::ConvertJavaStringToUTF16;
 using base::android::ConvertUTF16ToJavaString;
-using base::android::ScopedJavaLocalRef;
 
+namespace {
+
+// TODO(pliard): http://crbug.com/235909. Move WebKit shared timer toggling
+// functionality out of ContentViewStatistics and not be build on top of
+// WebKit::Platform::SuspendSharedTimer.
+// TODO(pliard): http://crbug.com/235912. Add unit tests for WebKit shared timer
+// toggling.
+
+// This tracks the renderer processes that received a suspend request. It's
+// important on resume to only resume the renderer processes that were actually
+// suspended as opposed to all the current renderer processes because the
+// suspend calls are refcounted within WebKitPlatformSupport and it expects a
+// perfectly matched number of resume calls.
+// Note that this vector is only accessed from the UI thread.
+base::LazyInstance<std::vector<int /* process id */> > g_suspended_processes =
+    LAZY_INSTANCE_INITIALIZER;
+
+// Suspends timers in all current render processes.
+void SuspendWebKitSharedTimers(std::vector<int>* suspended_processes) {
+  for (content::RenderProcessHost::iterator i(
+          content::RenderProcessHost::AllHostsIterator());
+       !i.IsAtEnd(); i.Advance()) {
+    content::RenderProcessHost* host = i.GetCurrentValue();
+    suspended_processes->push_back(host->GetID());
+    host->Send(new ViewMsg_SetWebKitSharedTimersSuspended(true));
+  }
+}
+
+// Resumes timers in processes that were previously stopped.
+void ResumeWebkitSharedTimers(const std::vector<int>& suspended_processes) {
+  for (std::vector<int>::const_iterator it = suspended_processes.begin();
+       it != suspended_processes.end(); ++it) {
+    content::RenderProcessHost* host = content::RenderProcessHost::FromID(*it);
+    if (host)  // The process might have been killed since it was suspended.
+      host->Send(new ViewMsg_SetWebKitSharedTimersSuspended(false));
+  }
+}
+
+}  // namespace
 
-// Return the first substring consisting of the address of a physical location.
+// Returns the first substring consisting of the address of a physical location.
 static jstring FindAddress(JNIEnv* env, jclass clazz, jstring addr) {
   string16 content_16 = ConvertJavaStringToUTF16(env, addr);
   string16 result_16;
@@ -33,12 +72,13 @@ static jstring FindAddress(JNIEnv* env, jclass clazz, jstring addr) {
 static void SetWebKitSharedTimersSuspended(JNIEnv* env,
                                            jclass obj,
                                            jboolean suspend) {
-  for (content::RenderProcessHost::iterator i =
-           content::RenderProcessHost::AllHostsIterator();
-       !i.IsAtEnd();
-       i.Advance()) {
-    content::RenderProcessHost* host = i.GetCurrentValue();
-    host->Send(new ViewMsg_SetWebKitSharedTimersSuspended(suspend));
+  std::vector<int>* suspended_processes = g_suspended_processes.Pointer();
+  if (suspend) {
+    DCHECK(suspended_processes->empty());
+    SuspendWebKitSharedTimers(suspended_processes);
+  } else {
+    ResumeWebkitSharedTimers(*suspended_processes);
+    suspended_processes->clear();
   }
 }